Defeating Modern Armor and Protection Systems

Abstract

An open source research and vulnerability study of main battle tanks and their protections systems revealed that current anti-tank weapons may not be suited to defeat modern threats. One example is the novel T-14 tank being developed and tested in the Russian army with its combined hard-kill and soft-kill active protection system AFGANIT / SHTORA, its new reactive armor MALACHIT as well as improved multi-component passive armor. Additionally, modern active protection systems currently developed in, e.g., Israel, the United States, and Germany feature also multi-sensor and multi-effector systems with drastically improved detection and intercept ranges, short system reaction times as well as protection against multiple threats attacking simultaneously and / or from similar directions. While known effectors and concepts may overcome fielded active protections systems, they are probably not suited in defeating such modern and even future systems. Countermeasures relying on high engagement velocities through improved kinetic energy projectiles or hypervelocity penetrators may provide a potential solution. Another promising concept generates directed, far-distance electromagnetic effects defeating sensors and communications systems of modern main battle tanks. After such a mission kill, a following salvo attack through an anti-tank or modern multi-role weapon will eventually lead to a catastrophic kill. Feasibility studies of these mobile electromagnetic effectors have already shown their high potential.

Full text

Proceedings of the 2019 Hypervelocity Impact Symposium
HVIS2019
April 14 - 19, 2019, Destin, FL, USA
HVIS2019-050
Defeating Modern Armor and Protection Systems
Markus Graswald *, Raphael Gutser, Jakob Breiner, Florian Grabner, Timo Lehmann,
and Andrea Oelerich **
TDW GmbH, Hagenauer Forst 27, 86529 Schrobenhausen, Germany
** WTD 91, Schießplatz 1, 49716 Meppen, Germany
Abstract
An open source research and vulnerability study of main battle tanks and their protections systems revealed that current anti-tank
weapons may not be suited to defeat modern threats. One example is the novel T-14 tank being developed and tested in the Russian
army with its combined hard-kill and soft-kill active protection system AFGANIT / SHTORA, its new reactive armor MALACHIT
as well as improved multi-component passive armor. Additionally, modern active protection systems currently developed in, e.g.,
Israel, the United States, and Germany feature also multi-sensor and multi-effector systems with drastically improved detection
and intercept ranges, short system reaction times as well as protection against multiple threats attacking simultaneously and / or
from similar directions. While known effectors and concepts may overcome fielded active protections systems, they are probably
not suited in defeating such modern and even future systems. Countermeasures relying on high engagement velocities through
improved kinetic energy projectiles or hypervelocity penetrators may provide a potential solution. Another promising concept
generates directed, far-distance electromagnetic effects defeating sensors and communications systems of modern main battle tanks.
After such a mission kill, a following salvo attack through an anti-tank or modern multi-role weapon will eventually lead to a
catastrophic kill. Feasibility studies of these mobile electromagnetic effectors have already shown their high potential.
Keywords: Main battle tank; active protection system; reactive / passive armor; kinetic energy / hypervelocity penetrator; high power electromagnetic.
1 Introduction
The enduring competition between weapon effectiveness and platform protection has already entered a new act. The
threat on main battle tanks imposed by various effectors such as anti-tank missiles (anti-tank (guided) missile, ATM /
ATGM) or shoulder-launched rockets (rocket propelled grenade, RPG) with tandem-shaped charge warheads (e.g., TOW 2A,
PARS3 LR), kinetic energy (KE) projectiles (e.g., M829 or DM 63), and top-attack munition with explosively formed
projectile (EFP) warheads (e.g., TOW 2B or SMArt) has been drastically increased over the last decades [1]. This lead to
recent developments with T-14 tanks (built on the standardized ARMATA track vehicle platform) in Russia using novel and
/ or improved active protection systems (APS), explosive reactive armor (ERA), and passive protection. Table 1 compares
Israeli main battle tank MERKAVA 4 with Russian tanks T-90 and T-14 showing significant improvements in terms of both
fire power and protection systems of the latter. It needs to be noted that data refers to 2013 sources and may be dependent
also upon environmental conditions, i.e., weather, day vs. night time. The greatest challenge, however, is offered through
the new generation of active protection system being developed.
This paper presents major results of a comprehensive survey on trends in developments on new main battle tanks and
their protection systems. Focussing on active protection systems, a classification scheme is provided and countermeasures
assessed. Two promising concepts, a combined kinetic energy effector and a mobile high power electromagnetic effector, are
introduced in detail along with simulation and experimental results of subsystems.
2 Technological trends in the field of main battle tank protection
The novel T-14 main battle tank currently tested in the Russian army was first fully shown at a parade in Moscow on
May 9th, 2015. After this initial rate, an ambitious series production of 2000+ units shall be completed in the early 2020s.
Although not all details on its capabilities are known, it uses a comprehensive protection concept with indirect and direct
measures: [1, 3]
•Reducing or changing signatures through stealth technologies in infrared and radar spectrum such as special coatings,
improved heat isolation, absorbing materials, cooling of exhaust gases, as well as an active, electromagnetic mine
protection system
* Corresponding author: Email markus.graswald@mbda-systems.de, Tel. +49 (8252) 99-7264.

Table 1. Overview comparing Israeli and Russian main battle tanks. [2]
Technical data MERKAVA 4 T-90 (A,S,M) T-14
Main weapon, caliber in mm 120 125 125 ... 152
Firing speed per min 4 8 10 ... 12
Detection range in m 4500 >5000 >5000
Maximum engagement range in m 4000 ... 6000 4000 ... 5000 7000 ... 8000
Mine protection Passive Active and passive Active
Active protection system TROPHY SHTORA AFGANIT
Reactive protection Yes Yes Yes
Armor equivalent in mm 700 ... 750 800 ... 830 >900
Engine power in PS 1500 1130 1200 ... 2000
Maximum mass in t 65 46.5 ... 48 50 ... 55
Maximum velocity in km/h 60 ... 65 60 ... 65 80 ... 90
Range in km 500 500 >500
•Avoiding hits by soft kill active protection systems like SHTORA-1
•Avoiding both hits and penetration by hard kill active protection systems like ARENA, DROZD, or novel AFGANIT
•Reducing the effectiveness through explosive reactive armor like KONTAKT-5, RELIKT, or novel MALACHIT
•Reducing the system impact through passive, multi-component ballistic protection based on novel high-strength
steels such as 44S-SW combined with non-metallic materials like ceramics, aramid fabrics, and plastics, e.g., PU
(polyurethane) or PE (polyethylene), providing an RHA (rolled homogeneous armor) equivalent of more than 900 mm
in the front section
Active protective systems of main battle tanks and armored vehicles are typically classified into soft or hard kill
systems. Their functionality is visualized in Figure 1. Based on a threat detected by sensors, a fire control solution will be
determined dependent upon threat analysis, its predicted trajectory, and the counter measure. A soft kill system distracts
the incoming threat either trough infrared (IR) emitters, jammer, or decoy/flares, or interrupts the line-of-sight by smoke
shells, while a hard kill system is designed to destroy the threat in a distinct and safe distance to the tank through deployed
or distributed blast/fragmentation projectiles, shaped charges or (multi) EFP, or directed high explosive (HE) charges. [1]
In a comprehensive literature and online search, a total of 26 active protection systems have been found and categorized
[3, 5]. Besides various Russian systems named earlier, SASLON/ZASLON as active and NOZH and DUPLET as reactive,
Ukrainian made protection systems are supposed to be highly effective. Israeli Trophy APS installed on MERKAVA MK4
tanks are known as combat proven in several armed conflicts. In NATO countries like the United States and Germany,
a number of both soft kill and hard kill active protection systems are developed and mounted onto main battle tanks or
armored vehicles such as PUMA and STRYKER. Turkey and South Korea develop their own systems called AKKOR and
KAPC for future integration on their main battle tanks ALTAY and K2, respectively.
Table 2 shows a classification scheme of APS with their protection against threat types, their sensor and effector
principle, and system aspects along with typical examples and essential data of Russian, Israeli, and American systems.
It differentiates between classical state-of-the-art systems like DROZD or SHTORA and modern or future systems like
AFGANIT or TROPHY since engagement concepts and weapon systems overcoming them may differ significantly. It
reveals that modern and potential future developments
•use a combination of sensors with different physical principles, long detection ranges, virtually no dead zones, and
capabilities to track multiple threats simultaneously
•rely on (a combination of) hard kill effectors with increased engagement ranges, and
•provide drastically reduced system reaction times from threat detection to countermeasure interaction
This allows the defeat of multiple – also high velocity – threats attacking simultaneously or successively from the same
or different directions. Further development trends concentrate on both sensors and countermeasures and indicate to use
active protection systems through cooperative engagements for other or even unprotected vehicles as well. Besides new and
modern tanks, classical tanks like T-72 or T-90 may also be upgraded with modern APS.
Figure 1. Principle of active protection systems visualized for hard and soft kill effectors. [4]

Table 2. Classification of active protection systems∗. [3]
Classification Parameter Classical APS Modern APS
Protection Single threats ATM, ATGM, RPG Most ATM, ATGM, RPG; in part KE
against Multiple threats No Yes, simultanously and/or from different
attack directions (AFGANIT, TROPHY,
IAAPS, IRON FIST)
Threat veloci-
ties
70 ...700 m/s, up to 1200 m/s (DROZD-
2)
1700 m/s (AFGANIT 1), 3500 m/s (AF-
GANIT 2)
Threat detec-
tion
Sensor type Mostly radar AESA, laser (RUS); combinations of
AESA, EO, IR, EW (TROPHY, IRON
FIST, FSAP, IAAPS), also integrated
into turret (AFGANIT, ARENA-E)
Zone Limited in Az, El (especially from top) 360 deg Az (typically), also 180 deg El
(AFGANIT)
Detection range 5 ... 75 m (typically) Up to 10 km (AFGANIT, IAAPS)
Tracking and
fire control
Sensor type Mostly radar Mostly AESA, especially for hard kill
Effector princi-
ple
Hard kill Mostly fragmenting or blast projectiles
(ADS)
Partly (multi) EFP (TROPHY, FSAP,
AFGANIT 2) or MG / cannon (AF-
GANIT 1), also through blast (FSAP,
IRON FIST)
Soft kill IR (SHTORA-1, IAAPS), decoy/
flares/smoke (POMALS, SHTORA-1)
Engagement
range
1... 10 m (typically) Up to 35 m
System aspects Reaction time >1 s <1 ms (AFGANIT), may also depend
upon threat velocity
Combinations of APS on one platform
(AFGANIT / SHTORA-1)
Various approaches have been identified to overcome active protection systems as visualized through an onion model
adapted for single or salvo engagements of effectors in Figure 2. These opportunities can also be combined for being more
effective and sustainable. The analysis revealed that existing anti-tank weapons and engagements principles exploiting
sensor-dead zones and using saturation attacks may still be suited against classical tanks, while they might be outdated
for current and future developments of active protection systems. Potential solutions meeting these challenges are, there-
fore, provided through a combined kinetic energy effector relying on super or hyper velocities and a mobile high power
electromagnetic effector aimed at defeating APS sensors. They are introduced in the following subsections. In addition,
anti-tank or multi-role missiles with tandem or new multi-effect warheads may still be effective against explosive reactive
and passive armor. They can also be used against a wider target set consisting of personnel, unarmored vehicles, and light
infrastructures.
3 Combined penetrator effector
Besides high explosive anti-tank missiles, kinetic energy projectiles like DM 63 or M829 provide a high threat potential
against classical main battle tanks. They are typically fired from 120 mm caliber guns and reach high velocities 1000 m/s
∗Acronyms not introduced earlier: active electronically scanned array (AESA), electro-optical (EO), infrared (IR),
electronic warfare (EW), azimuth (Az), elevation (El), machine gun (MG).
Figure 2. Adapted onion model showing various opportunities for effectors to overcome active protection systems
that can be achieved through single or salvo engagements.

to penetrate both reactive and passive armor. Modern tanks with active protection systems, improved reactive and passive
armor may, however, drastically decrease their performance.
Supplementing a kinetic energy penetrator with a precursor shaped charge provides an incredible excess velocity so
that the EFP may be fired well outside the APS engagement range hitting unrecognized the explosive reactive armor and
initiating it. The concept is visualized in Figure 3. An EFP charge may also serve as a deception device for APS, so that the
KE penetrator survives and eventually engages the main target effectively. The precursor charge consists of a high strength
metal such as tantal, a high-performance octogene-based high explosive charge like a KS33 or P31 with a reactive detonation
wave shaper and a shock-hardened inline (electronic safe-and-arm device, ESAD) fuze system embedded into light weight
titanium structure. A sub-caliber, high L/D tungsten penetrator is located behind and may be further improved through
reactive materials. This cost-efficient and robust lethal package can be integrated into various systems like a hyper-velocity
missile or an armor piercing fin-stabilized discarding sabot (APFSDS) munition.
The EFP precursor charge was designed meeting desired velocities of >800 m/s, L/D ratios of 5, and fin-stabilization
measures with the hydrocode SPEED [6]. Its effectiveness against various targets was modeled using a 3D Eulerian mesh
as well. Results of a representative explosive reactive armor module consisting of Comp B (RDX/TNT) applying the
History Variable Reactive Burn (HVRB) initiation model are shown in Figure 4. They indicate that the EFP can penetrate
inert flyer plates and initiate the explosive layer at least with a deflagration or low-order detonation reaction. Assuming a
sufficient timely stand-off, the ERA target should be cleared for the succeeding penetrator killing the main target with its
remaining passive armor.
4 High power electromagnetic effector
A mobile high power electromagnetic (HPEM) effector integrated into an anti-tank missile as displayed in Figure 5 seems
interesting for defeating active protection systems sensors and communication devices of main battle tanks. Early studies
generating electromagnetic effects through explosive devices date back several decades, e.g., [7, 8, 9] and recent feasibility
studies of have already shown their high potential [10, 11]. The concept consists of an explosively driven flux compression
generator (FCG), an electrical opening switch and the subsequent shaping of the electrical pulse into an high frequency (HF)
radio signal (e.g., by applying a magnetron) that is radiated through an antenna system. This enables a compact design for
integration into mobile applications such as missiles, shoulder-launched munitions, or artillery shells. The following section
describes the design of an FCG and several proof-of-principle firing tests as well as a HF generator and directed antenna
investigating the vulnerability of electronic components.
4.1 Proof-of-principle tests on prototype FCGs
The working principle of a flux compression generator can be explained by using the transient Maxwell equations. Its main
purpose is generating a short-time high level electric power peak by converting chemical energy into kinetic energy – released
by detonating a high explosive charge – and eventually into electrical power. This changes the magnetic field and induces
an Eddy current similar to an electrical motor. The high-explosive driven magnetic flux compression generator shown in
Figure 3. Rendered artist impression of a high velocity effector combining an EFP precursor charge with a kinetic
energy penetrator.
(a) Before penetration. (b) After penetration and HE initation.
Figure 4. 3D SPEED hydrocode simulation of an EFP attacking a representative ERA target.

Figure 5. Directed HPEM missile designed against active protection systems of main battle tanks.
Figure 6 consists of a capacitor bank, a stator coil (solenoid), an armature filled with a HE charge, and a load switch. This
system operates through these three major steps:
•Seeding current: An initial magnetic flux density is required to start the process which can then be compressed by
the system. This flux density has to be provided conventionally by an appropriate high power source such as a Marx
Generator or a capacitor bank that generates the seeding current.
•Flux compression: After charging the solenoid with the seeding current and establishing a high magnetic flux density
within the system, the conventional power generator is removed from the system and the detonation process starts.
The expansion of the armature creates an electric contact with the coil/solenoid compressing the magnetic flux in a
very short time. This results in an instantaneous increase of the magnetic energy density within the system allowing
the generation of currents of several 100 kA.
•Power conversion: The generated power needs to be transmitted to a load such as a HF generator with an antenna
structure. For the flux compression process, the load switch needs to be closed in order to enable a high current for
flux compression. This short circuit switch needs to be opened in a short time transmitting the power to the load.
An explosive electric opening switch is a possible option to realize fast switching.
Prototypes of high explosive driven generators, a test setup and diagnostics including a Rogowski probe for current
measurements were developed for proof-of-principle trials at Schrobenhausen site. Circuits for the flux compression generator
and detonator initiation were galvanically separated. Test setups with FCG prototypes are displayed in Figure 7 (with
capacitor bank not shown). Figure 8 shows a successfully measured output current from the FCG (red line) prototype
and shunt (blue line) during detonation. The detonation of the FCG was timed to the positive peak of the pulse generator
resulting in an output current of several hundreds of kA in the microsecond regime. This complies to a current amplification
with a factor of approx. 30 that was basically predicted through the system simulation.
FCGs can be further optimized through increasing the seeding current, the forming of the magnetic field and the
subsequent timely trigger for initiating the high explosive charge. An appropriate design of the armature and solenoid,
the type of high explosive charge, and a precise manufacturing and assembly process are also important. Another develop-
ment step is the interface design between the current power output and HF generator to fulfil the radiation characteristic
requirements. This current to HF signal transformation depends also on the targets of interest and operational endgame
settings.
4.2 Vulnerability tests of representative components
Since microcontrollers and FPGAs serve as subsystem controllers in a variety of applications such as sensoring, navigation,
and other data processing, a malfunction of these devices lead usually to a critical system state and may cause overall
system failures as well. Their damage levels are typically classified as follows:
•Level 1: disturbance of core functionalities of electronic components while the interference signal is active
Figure 6. 3D view of a flux compression generator including detonator and cables to the capacitor bank.

(a) Test setup T16211. (b) Test setup T68873. (c) Setup T68874.
Figure 7. Testing the flux compression generator prototype.
Figure 8. Rogowski probe measurement of current generated by the flux compression generator prototype (red line)
and capacitor bank shunt current (blue line).
•Level 2: temporary disturbance of core components until system reboot
•Level 3: permanent damages of components – their exchange is required for proper operations
Besides these electronic components, transmission lines such micro strip lines and coaxial lines are considered as well
since they are used in integrated circuits and for connecting all electronic devices transmitting signals in the high frequency
domain. These lines are modeled in COMSOL Multiphysics [12] and eventually exposed to electrical fields. Figure 9a shows
a coaxial line modeled through three concentric circles, a dielectricum between conductor lines, and ports at conductor ends:
electrical field lines pointing from the inner to the outer line, magnetic field lines passing in inconcentric circles parallel to
both lines, and a pointing vector pointing into the plane. The model implementation is initially simulated using a test signal
and without outer influences for verifying typical line characteristics such as damping depending upon signal frequency or
impedance with analytical calculations and experimental data. Figure 9b shows a good correlation of simulation results
with analytical and literature data except in the lower frequency domain.
(a) 3D field vectors: electrical one in red, magnetic one
in blue, and pointing vector in green.
(b) Comparing literature data, theoretical
and simulated damping results.
Figure 9. Simulation of a coaxial cable with COMSOL Multiphysics.

Shielding electronics against electromagnetic fields was also investigated through simulations. Figure 10a displays a
copper Faraday cage that provides a perfect shielding. Openings such as slits and grits are mostly required for practical
reasons. They are also used in radar sensor systems and communication devices and allow a transmission of electromagnetic
signals as exemplified in Figures 10b and 10c.
A representative microcontroller (LPC2103FBD48) is also modeled in a COMSOL Multiphysics simulation [12] and
its response on externally generated electromagnetic fields evaluated. The induced current into the component is simulated
and the resulting damage evaluated through the given CMTI (Common mode Transient Immunity) value. Figure 11 shows
the microcontroller model and the simulated induced current at a given field strength. If the component dependent CMTI
value measured through means of surge protection measurement (SPM) is exceeded, the system will usually shutdown.
Permanent component damages can be assumed by exceeding this value by a factor of 5.
In an experimental setup for subcomponent tests, a continuous and a pulsed magnetron were used for generating
HF signals that were transmitted through a horn antenna. Figure 12 shows a simulated far field and gain of a typical
horn antenna with CST Microwave Studio [13]. The electrical field strength is measured robustly with Ddot sensors. The
effectiveness of the emitted signal is eventually evaluated against commonly used FPGAs such as an Altera MAX10 and
Xilinx Spartan6 as well as microcontrollers like an Intel PIC18.
Development boards with these two embedded FPGAs and a microchip were used for vulnerability tests at the anechoic
chamber located at Schrobenhausen site. The test setup is shown in detail in Figure 13. Each board uses a different set of
input and output devices, e.g., LEDs, switches, VGA port, GPIO pins. Hundreds of tests of these board were performed.
During each test campaign, the variation on supply voltages besides a logic signal in the domain of kilohertz have been
measured. Parameters varied include the distance and direction of the antenna to the component relating to the field
strength as well as pulse and idle times of the interference signal.
The experimental investigation shows a variety of results. The transmitted wave form of the signal, e.g., either a
continuous RF signal or a pulsed rectangular wave signal, remains the same in the measured signal of the boards. While
a dependency of the results on pulse power periods and their power-to-idle ratio could not be observed, the electrical field
strength and angle of attack are significant parameters. Changing this angle of attack of the antenna to the component, it
was proven that individual angles exist where sudden increases or decreases of the signal voltage measured occur. Parameter
settings for best and worst signal deflections were eventually identified. Damage levels observed vary widely between all
three components investigated. While a level 1 damage was mostly observed, a level 2 was only noticed infrequently and a
level 3 not at all. This might be changed through applying higher field strengths or through shorter wave lengths providing
more efficient disturbances at a given field strength. These experimental results will be used for verifying a simulation of
the electronic components modeled in LT Spice.
5 Conclusions
The ongoing development of a new generation of main battle tanks with its improved protection systems provides a challenge
for existing anti-tank effectors. The study identified vulnerabilities of modern and future active protection systems. Several
potential counter measures were assessed and two promising concepts down selected, i.e., a combined penetrator effector
relying on excess velocities and a high power electromagnetic effector for defeating sensor and communication devices. The
theoretical and experimental investigations performed enable detailed concept designs for different system applications. In
future, it is planned to build prototypes of complete effector systems for performing experimental tests against relevant
military targets based on operational scenarios and associated endgame settings.
(a) Faraday cage. (b) Slits. (c) Grit.
Figure 10. Assessment of geometric shielding measures against electromagnetic radiation.
(a) COMSOL model. (b) Current vs. frequency at a given field strength.
Figure 11. Vulnerability of a microcontroller evaluated through COMSOL Multipysics simulations.

(a) 3D far field. (b) Antenna gain.
Figure 12. Horn antenna simulation providing an directional electromagnetic effect.
(a) Site overview. (b) Close-up view on test board.
Figure 13. Test setup with test board, video camera, horn antenna, and magnetron (from left to right) in an
anechoic chamber.
Acknowledgements
The authors gratefully acknowledge the financial support by Meppen proving ground WTD 91, GF-440, and BAAINBw K1.5.
References
1. R. Holthaus. Plattformschutz – Hard- und Softkill-Systeme. Strategie & Technik, Nov 2011.
2. http://youinf.ru/armata-vs-mercava/. Accessed Nov 2015.
3. M. Graswald. Recherche und Klassifikation aktiver Schutzsysteme inklusive des Gesamtschutzes moderner
Kampfpanzer. Number TDW-TN-EN-15-0017. TDW GmbH, Schrobenhausen, Feb 2016.
4. J. E. Staff. Developments in APS technologies. https://ihsmarkit.com/research-analysis/developments-in-
active-protection-system-aps-technologies.html, Oct 2017. Accessed Nov 2018.
5. M. Graswald and R. Gutser. Recherche zum Gesamtschutz moderner Kampfpanzer und Wirksystemtechnolo-
gien gegen Aktivschutzsysteme/ UAV-Schw¨
arme. Number TDW-TN-EN-17-0012. TDW GmbH, Schroben-
hausen, Dec 2017.
6. N. N. SPEED v 3.1 Users Manual. Numerics GmbH, Petershausen, 2018.
7. C. M. Fowler and L. L. Altgilbers. Magnetic Flux Compression Generators: a Tutorial and Survey. Los
Alamos National Laboratory, 1975.
8. E. Kleinschmidt. Studie zur Erzeugung elektro-magnetischer Pulse (EMP) mit Sprengladungen (Teil 1). Num-
ber TDW-TN-PE4-96-0043. TDW GmbH, Schrobenhausen, 1996.
9. E. Kleinschmidt. Studie zur Erzeugung elektro-magnetischer Pulse (EMP) mit Sprengladungen (Teil 2). Num-
ber TDW-TN-PE4-96-0043. TDW GmbH, Schrobenhausen, 1996.
10. V. K. Chernyshev. Superpower explosive magnetic energy sources. In Proceedings of the International Work-
shop High Energy Density Hydrodynamics, Novosibirsk, Russia, 2004.
11. P. Appelgren. Modeling of a Small Helical Magnetic Flux-Compression Generator. IEEE Transactions on
Plasma Science, 36(5), 2008.
12. N. N. COMSOL Multiphysics version 5.3. COMSOL AB, Stockholm, Sweden, 2017.
13. N. N. CST EMC Studio User Manual. Dassault Systems, V´elizy-Villacoublay, France, 2017.