Comparison of free geophysics software

This is a list of free and open-source software for geophysical data processing and interpretation. The list is split into broad categories, depending on the intended use of the software and its scope of functions.

Notice that 'free and open-source' requires that the source code is available. Simple being 'free of charge' is not sufficient—see gratis versus libre. The reader interested in freeware (just free of charge) software is referred to the list of freeware geophysics software.

Reflection seismic processing packages

These are full-featured reflection seismology processing packages, with support for modeling, imaging, and inversion. They are relatively low-level and in some cases have their own data formats and involve learning an extensive syntax or meta-language.

Name Description Originator License Platforms Language Notes
Madagascar[1] Multidimensional data analysis including seismic processing Sergey Fomel and others GPL Cross-platform C, C++, Python Programming Interfaces to Fortran 77, Fortran 90, Python, Java, MATLAB, Julia.
FreeUSP[2] Seismic processing Amoco, BP Custom Unix, Linux Fortran 77, C Includes OBS Node Survey Simulator, BP Anisotropic Velocity-Analysis Benchmark
FreeDDS[3] Seismic processing Amoco, BP Custom Unix, Linux Fortran 77, C Generic format (SEGY, SU, SEPlib, USP)
PSEIS-OSS[4] Parallel seismic processing Randy Selzler GPL Unix, Linux Fortran 77, C Generic format (SEGY, SU, SEPlib, USP, Madagascar)
CWP/SU (Seismic Unix)[5] Seismic processing Stanford, Colorado School of Mines BSD-style Unix, Linux, OS X, Cygwin 32 C, some Fortran 77 World's most widely used (82 countries and territories).
CPSeis[6] Seismic processing ConocoPhillips MIT Cross-platform Fortran 90, C++
SPARC[7] Seismic processing ARCO GPL Cray Fortran
SEPlib[8] Seismic processing Stanford University Custom Cross-platform Fortran, C
GeBR[9] Seismic processing Various contributors, Brazil GPL Linux C Interfaces with SU, Madagascar, etc.
OpenSeaSeis[10] Seismic processing Bjorn Olofsson, now property of the Colorado School of Mines BSD-style Linux, Windows, OS X C, C++, Java Interfaces with SU data. Reads most common SEGY and a subset of SEGD formats.

Reflection seismic processing utilities

These packages offer some subset of functionality of the full processing packages in the previous section.

Name Description Originator License Platforms Language Notes
BotoSeis[11] Seismic processing Williams Lima, Brazil GPL Cross-platform Java Workflow builder; interfaces with SU, Madagascar, etc.
Delivery[12] Bayesian inversion CSIRO GPL, BSD-style Cross-platform Java
GSEGYView[13] Display SEG-Y files Vladimir Bashkardin GPL Cross-platform Fortran, C
GPLib++[14] Seismic and magnetotelluric processing Max Moorkamp, Dublin Inst. Adv. Studies GPL Unix, Linux C++
JavaSeis[15] Pre-stack seismic I/O ARCO CPL Cross-platform Java
kogeo[16] Geophysical analysis and visualization University of Hamburg GPL Windows C++
Mines JTK[17] Signal processing and display Dave Hale, Colorado School of Mines CPL Cross-platform Java
JRG[18] Modeling and basic processing John Louie, University of Nevada Custom Cross-platform Java
Jive3D[19] Modeling and tomographic inversion James Hobro, University of Cambridge Custom Unix, Linux Fortran GMT and other libraries
PySIT[20] Imaging and inversion Russell Hewett & Laurent Demanet, MIT BSD 3-clause Unix, Linux Python
SegDSee[21] Display SEG-D and SEG-B files Sergey Pavlukhin Custom Cross-platform C++, Qt
segyio[22] Read and write SEG-Y files Equinor LGPL Cross-platform C, Python
Segpy[23] Read and write SEG-Y files Rob Smallshire, Thomas Mejer Hansen LGPL Cross-platform Python Fork of defunct SegyPY
segy-py[24] Read SEG-Y files Kurt Schwehr, Google Custom Cross-platform Python Various FOSS packages
SeismiGraphix[25] Read and view SEG-Y, SEG-D, Seismic Unix and Javaseis. View and remap headers Abel Surace Custom Cross-platform Java
SIOSEIS[26] Seismic reflection and refraction processing Paul Henkart, SIO BSD Cross-platform gfortran, gcc
SLIMpy[27] Processing front end Felix Herrmann, Univ. of British Columbia LGPL Cross-platform Python Interfaces with SU, Madagascar, etc.
WaveletExtractor[28] Well-ties CSIRO GPL, BSD-style Cross-platform Java

Nonreflection seismic processing utilities
Name Description Originator License Platforms Language Notes
ObsPy[29] Seismology toolbox Moritz Beyreuther et al. LGPL Cross-platform Python Uses Numpy and Cython
PAMGUARD[30] Passive acoustic monitoring for marine mammals Multiple workers GPL Linux, Windows, OS X Java Plug-in-able
SCEC Broadband Platform[31] Ground Motion Simulation SCEC Community Modeling Environment Apache 2 Linux Python, C, Fortran Uses Numpy and SciPy
Sesarray[32] Signal processing for ambient vibrations Joseph Fourier University, University of Potsdam GPL Linux, Windows, OS X C, C++ Includes geopsy (signal processing) & dinver (inversion)
Seismic Handler[33] Signal processing for earthquakes SZGRF GPL Linux, Solaris C, Python
STK[34] Signal processing for earthquakes Dominique Reymond GPL Unix, Linux, Windows C
TauP[35] Travel-time & ray-path calculation University of South Carolina GPL Cross-platform Java
smartRefract[36] Refraction seismic interpretation Simone Pittaluga GPL Cross-platform Java Based on GRM (Palmer)

Modeling and inversion packages
Name Description Originator License Platforms Language Notes
devito[37] Symbolic finite difference engine, including seismic modeling and inversion Fabio Luporini, Matthias Louboutin, et al. MIT Cross-platform Python Uses Numpy and SymPy
Fatiando a Terra[38] Geophysical modeling and inversion Leonardo Uieda et al. BSD Cross-platform Python Uses Numpy and Cython
PyGMI[39] 3D interpretation and modelling of magnetic and gravity data Patrick Cole GPL Cross-platform Python
SimPEG[40] Simulation and Parameter Estimation in Geophysics Rowan Cockett et al. MIT Cross-platform Python Uses Numpy and SciPy
pyGIMLi[41] Geophysical Inversion and Modelling Library Carsten Rücker, Thomas Günther, and Florian Wagner Apache 2 Cross-platform Python Uses Numpy
OCCAM1DCSEM[42] An Inversion Program for Generating Smooth 1D Models from Controlled-Source Electromagnetic and Magnetotelluric Data. Kerry Key, SEMC GPL Cross-platform Fortran Optional plotting and editing routines are in Matlab.
2DMT[43] Occam's inversion for 2D magnetotelluric (MT) modeling Steven Constable et al., SEMC Unclear Cross-platform Fortran Optional plotting and editing routines are in Matlab.
empymod[44] Full 3D electromagnetic modeller for 1D VTI media Dieter Werthmüller Apache 2 Cross-platform Python Uses Numpy and SciPy
extrEMe[45] Accurate and scalable 3-D MT forward solver based on a contracting integral equation method M. Kruglyakov, A. Geraskin, A. Kuvshinov modified GPL 2 Cross-platform C#
GIEM2G[46] Gnu Integral Equation Modeling in ElectroMagnetic Geophysics Mikhail Kruglyakov, Lidia Bloshanskaya GPL 2 Cross-platform Fortran
gprMax[47] Ground Penetrating Radar (GPR) 3D modelling Antonis Giannopoulos, Craig Warren, et al. GPL 3 Cross-platform Python, Cython

Visualization, interpretation, analysis packages
Name Description Originator License Platforms Language Notes
Geoscience Analyst[48] Import, visualize, annotate, save, and distribute 3D geoscientific data types and models Mira Geoscience QLM Windows C++, Python Version 3.1 and above provides a Python API to connect to open source software and view results in a 3D visualization environment designed specifically for the geosciences and mining.
OpendTect[49] Geoscience interpretation and visualization dGB Earth Sciences GPL or custom Cross-platform C++ Interfaces with Petrel, Madagascar, GMT, Google Earth/Maps
GeoTriple for Oil&Gas Exploration[50] Geoscience data management, display and analysis Geoforge project LGPL Cross-platform Java Interfaces with WorldWind
GeoCraft[51] Geophysical analysis and visualization ConocoPhillips MIT Cross-platform Java
qiWorkBench[52] Geophysical interpretation and visualization BHP Billiton Petroleum GPL, BSD Cross-platform Java
Generic Mapping Tools[53] Map generation and analysis Lamont-Doherty and University of Hawaii GPL Cross-platform C Implemented in OpendTect
ParaViewGeo[54] Geoscience extension of ParaView Kitware ParaView, MIRARCO BSD Cross-platform C++, Python Oriented towards mining
GI[55] Geophysical interpretation and visualization Unclear Cross-platform C++, Qt Alpha version
FischerLab[56] Fischer Plots and Sequence Stratigraphy Adewale Amosu & Yuefeng Sun, Texas A&M University Modified BSD Cross-Platform Matlab Free to use
EMP[57] Processing of raw time series of MT/AMT/RMT and controlled source data. Visualization of MT data on map Arseny Shlykov MIT Windows C# Free to use

Not true free and open-source projects

The following projects are not free and open-source. They have unknown licensing, licenses which place some restriction on use or redistribution, or depend on non-open-source software like MATLAB, and thus do not meet the Open Source Definition from the Open Source Initiative. (For example, the license may rule out use by certain people or for certain purposes, e.g., in a commercial context.) They are included here because they may be of interest for those in an academic environment or access to tools like MATLAB.

Name Description Originator License Platforms Language Notes
GeoFEST[58] Fault and terrain visualization Greg Lyzenga & Jay Parker, Jet Propulsion Laboratory Unclear Unix, Linux C Hosted by Open Channel Foundation[59]
MSLT[60] Finite element stress-strain modeling Peggy Li & Herb Siegel, Jet Propulsion Laboratory Unclear Unix, Linux, OS X C
GeoSeis[61] Processing seismic refraction data Muhammed Celik, Kocaeli University Freeware Windows Visual Basic Fully free after v. 1.3.8
MARE2DEM[62] 2D Inversion of CSEM and MT Data Kerry Key, Scripps Institution of Oceanography Freeware, GNU open source OS X, Linux, Windows Fortran Free to use, needs a valid MATLAB license to build models
GPRSoft Lite[63] GPR Data Visualization Geoscanners AB Freeware Windows GSF, DZT, RAD3, DT1, formats supported
GP Workbench[64] GPR processing USGS Unclear Windows C++ SU format
Seismic Lab[65] Seismic processing toolbox Mauricio Sacchi, University of Alberta GPL Cross-platform MATLAB Needs MATLAB
CREWES[66] Seismic processing toolbox Gary Margrave, University of Calgary Custom, free for non-commercial use Cross-platform MATLAB Needs MATLAB
SegyMAT[67] Read and write SEG-Y files Thomas Mejer Hansen, Univ. of Copenhagen LGPL Cross-platform MATLAB Needs MATLAB
IMAGE2SEGY[68] Image converter Marcel.lí Farran, Institut de Ciències del Mar Creative Commons Cross-platform MATLAB Needs MATLAB & SegyMAT
SW3D[69] Seismic processing Vlastislav Cerveny, Charles University Unclear
rayinvr[70] 2D traveltime inversion Colin Zelt, Rice University Custom, non-commercial use only Unix, Linux Fortran 77, C
fast[71] 3D traveltime tomography Colin Zelt, Rice University Custom, non-commercial use only Unix, Linux Fortran 77, C
passeis[72] Passive seismic analysis Haishan Zheng, University of Saskatchewan Unclear Cross-platform MATLAB Needs MATLAB
seismon[73] Processing for earthquakes Stefan Mertl GPL Cross-platform MATLAB Needs MATLAB
PyShottab[74] Processing for ocean-bottom seismic Dalhousie University Unclear Cross-platform Python Windows binary
IGeoS (formerly SIA)[75] Geophysical processing and analysis University of Saskatchewan Custom, free for non-commercial use Unix, Linux C++ Interfaces with SU, GMT
Seizmo[76] Global seismic analysis Garrett Euler, Washington University in St. Louis Unclear Cross-platform MATLAB Octave-compatible
GISMO[77] Seismic waveform and earthquake catalog analysis Glenn Thompson, University of South Florida Freeware Windows, MacOSX, Linux Matlab Fully free
MVSPsoft[78] Borehole Seismic Data Processing and Interpretation Mohammed Farfour, Sultan Qaboos University Freeware Windows Matlab Fully free
WheelerLab [79] Sequence Stratigraphic Analysis and Chronostratigraphic Analysis (Wheeler Diagrams) Adewale Amosu & Yuefeng Sun, Texas A&M University Modified BSD Cross-Platform MATLAB Needs Matlab and SegyMAT

Collections
Name Description Originator License Platforms Language Notes
SEG Software Repo[80] Open source codes that were made available together with published articles in the journal Geophysics by the Society of Exploration Geophysicists SEG. Various authors SEG license and others Variable Variable Static repo. Maintained versions might be found on other places.
P233 Suite[81] Open source codes for EM data (1D, 2D, 3D) from 25 years of investigation by CSIRO, funded by AMIRA. CSIRO Public Domain Cross-Platform Fortran
Markku Pirttijärvi[82] Free (but mostly not open-source) software by Markku Pirttijärvi; mostly EM, gravity and magnetic data. Markku Pirttijärvi Free to download Windows Fortran Free, not open source
Geoscience Australia's

Airborne Electromagnetic Inversion Software[83]

 Open source codes for inverting and forward modelling airborne electromagnetic (AEM) data:

GAFORWARDMODELTDEM - 1D forward modelling . GALEISBSTDEM - deterministic 1D sample by sample inversion. GARJMCMCTDEM - stochastic 1D sample by sample inversion

Geoscience Australia

Ross C. Brodie

 Creative Commons 4.0 Attribution (BY). Free to download Cross-Platform C++, Some third party software dependencies. (Specified within).

Probably defunct projects

The following projects have seen very little activity for more than a year.

Name Description Originator License Platforms Language Notes
openGPR[84] GPR processing and interpretation Mats Schuh GPL Linux Python No longer in active development
OpenICarre Integrated interpretation system IFP
MagIC-Py[85] Magnetic data processing Python
geoid[86] Geological mapping
ART[87] Ray tracing
GPCPP[88]
Seismic Refraction Tomography[89] GPL

References
  1. "Madagascar". reproducibility.org. Retrieved 2016-06-13.
  2. "FreeUSP Download". freeusp.org. Retrieved 2016-06-13.
  3. "Data Dictionary System: Home". freeusp.org. Retrieved 2016-06-13.
  4. "Archived copy". Archived from the original on 2013-06-14. Retrieved 2019-07-08.CS1 maint: archived copy as title (link)
  5. "CWP". cwp.mines.edu. Archived from the original on 2016-06-14. Retrieved 2016-06-13.
  6. "It works!". Archived from the original on 2009-08-26. Retrieved 2016-06-13.
  7. "Index of /Arco". freeusp.org. Retrieved 2016-06-13.
  8. "Home [Stanford Exploration Project]". sepwww.stanford.edu.
  9. "GêBR Project". gebrproject.com. Retrieved 2016-06-13.
  10. "CWP". cwp.mines.edu. Archived from the original on 2014-04-06. Retrieved 2016-06-13.
  11. "BotoSeis download | SourceForge.net". botoseis.sourceforge.net. Retrieved 2016-06-13.
  12. "CSIRO Petroleum and Geothermal research". www-old.dpr.csiro.au. Archived from the original on 2018-02-02. Retrieved 2018-02-01.
  13. "gsegyview download | SourceForge.net". sourceforge.net. Retrieved 2016-06-13.
  14. "GPLIB++: GPLib++ documentation". gplib.sourceforge.net. Retrieved 2016-06-13.
  15. "JavaSeis download | SourceForge.net". javaseis.org. Retrieved 2016-06-13.
  16. "kogeo - a free and open toolkit for 2d/3d seismic data analysis". kogeo.de. Retrieved 2016-06-13.
  17. "Dave Hale | mines jtk". inside.mines.edu. Retrieved 2016-06-13.
  18. "JRG - Seismic Processing on Any Computer". crack.seismo.unr.edu. Archived from the original on 2016-06-17. Retrieved 2016-06-13.
  19. James W. D. Hobro. "Jive3D". bullard.esc.cam.ac.uk. Archived from the original on 2011-08-07. Retrieved 2016-06-13.
  20. "PySIT Seismic Imaging Toolbox for Python". pysit.org. Retrieved 2016-06-13.
  21. S.Pavlukhin. "ДМНГ – Программы". dmng.ru. Archived from the original on 2016-03-04. Retrieved 2016-06-13.
  22. "GitHub - statoil/segyio: C and Python library for reading and writing SEG-Y files". github.com. Retrieved 2017-04-26.
  23. "GitHub - sixty-north/segpy: A Python package for reading and writing SEG Y files". github.com. Retrieved 2016-06-13.
  24. "Index of /~schwehr/software/seismic-py". vislab-ccom.unh.edu. Retrieved 2016-06-13.
  25. "SeismiGraphix".
  26. "Seismic processing system SIOSEIS". sioseis.ucsd.edu. Retrieved 2016-06-13.
  27. "SLIMpy: SLIMpy". slim.eos.ubc.ca. Archived from the original on 2016-08-26. Retrieved 2016-06-13.
  28. http://www.csiro.au/products/WaveletExtractor.html
  29. "Home · obspy/obspy Wiki · GitHub". github.com. Retrieved 2016-06-13.
  30. "PAMGuard | Passive Acoustic Monitoring |PAM Open Source Software - PAMGuard". pamguard.org. Retrieved 2016-06-13.
  31. "Broadband Platform - SCECpedia". scec.usc.edu. Retrieved 2016-06-13.
  32. "Geopsy home: software applications for ambient vibration techniques". geopsy.org. Retrieved 2016-06-13.
  33. "Seismic Handler". seismic-handler.org. Retrieved 2016-06-13.
  34. D Reymond. "STK : Seismic ToolKit written with GTK+". seismic-toolkit.sourceforge.net. Retrieved 2016-06-13.
  35. "USC Seismology - TauP". seis.sc.edu. Retrieved 2016-06-13.
  36. "smartRefract download page". vs30.it. Retrieved 2016-06-13.
  37. "Devito". devitoproject.org. Retrieved 2019-01-28.
  38. "Fatiando a Terra: modeling and inversion — fatiando 0.4 documentation". fatiando.org. Retrieved 2016-06-13.
  39. "Google Project Hosting". Retrieved 2016-06-13.
  40. "SimPEG: Simulation and Parameter Estimation in Geophysics". simpeg.xyz. Retrieved 2020-06-18.
  41. "— GIMLi - Geophysical Inversion and Modelling Library". www.pygimli.org. Retrieved 2017-06-02.
  42. Newman, Steven Constable, Kerry Key, Robert. "Scripps Institution of Oceanography Marine EM Laboratory | Research | Occam 1D CSEM and MT Inversion". marineemlab.ucsd.edu. Retrieved 2017-06-02.
  43. Newman, Steven Constable, Kerry Key, Robert. "Scripps Institution of Oceanography Marine EM Laboratory | Research | Occam 2D MT Inversion". marineemlab.ucsd.edu. Retrieved 2017-06-02.
  44. "empymod". empymod.github.io. Retrieved 2017-06-02.
  45. "extrEMe". bitbucket.org/em_geophysics/extreme. Retrieved 2017-12-26.
  46. "GIEM2G". github.com/DarthLaran/GIEM2G. Retrieved 2017-12-26.
  47. "gprMax". www.gprMax.com. Retrieved 2018-01-29.
  48. https://mirageoscience.com/mining-industry-software/geoscience-analyst/
  49. "OpendTect - Free Open-source Seismic Interpretation Software System". opendtect.org. Retrieved 2016-06-13.
  50. "GeoTriple - Oil&Gas Exploration - About". geoforge.org. Retrieved 2016-06-13.
  51. "GeoCraft Github repository". github.com. Retrieved 2016-08-31.
  52. http://qiworkbench.org%5B%5D
  53. "Wiki - GMT - GMT — The Generic Mapping Tools". gmt.soest.hawaii.edu. Retrieved 2016-06-13.
  54. "Acfas-Sudbury". paraviewgeo.mirarco.org. Retrieved 2016-06-13.
  55. "GI download | SourceForge.net". sourceforge.net. Retrieved 2016-06-13.
  56. "View PDF". www.searchanddiscovery.com. Retrieved 2017-12-02.
  57. "EMP main". www.csrmt.info. Retrieved 2019-04-21.
  58. "GeoFEST". physics.hmc.edu. Retrieved 2016-06-13.
  59. "Open Channel Foundation: Welcome". openchannelfoundation.org. Archived from the original on 2001-03-31. Retrieved 2016-06-13.
  60. "Open Channel Foundation: MSLT". openchannelfoundation.org. Archived from the original on 2016-08-16. Retrieved 2016-06-13.
  61. "GeoSeis - Ana Sayfa". geoseis.tr.gg. Retrieved 2016-06-13.
  62. "MARE2DEM | Modeling with Adaptively Refined Elements for 2D Electromagnetics". mare2dem.ucsd.edu. Retrieved 2016-06-13.
  63. "GPRSoft – Post-Processing GPR Software". geoscanners.com. Archived from the original on 2016-06-03. Retrieved 2016-06-13.
  64. "USGS Open-File Report 2006-1365: GP Workbench Manual: Technical Manual, User's Guide, and Software Guide". pubs.usgs.gov. Retrieved 2016-06-13.
  65. "Signal Analysis and Imaging Group - SeismicLab - Matlab Scripts for Seismic Data Processing". seismic-lab.physics.ualberta.ca. Retrieved 2016-06-13.
  66. "CREWES Matlab Toolbox". crewes.org. Retrieved 2016-06-13.
  67. "SegyMAT : A Matlab and Octave toolbox for reading and writing SEG-Y formatted files". segymat.sourceforge.net. Retrieved 2016-06-13.
  68. "IMAGE2SEGY". icm.csic.es. Archived from the original on 2016-03-04. Retrieved 2016-06-13.
  69. "SW3D". sw3d.mff.cuni.cz. Retrieved 2016-06-13.
  70. "RAYINVR". terra.rice.edu. Retrieved 2016-06-13.
  71. "FAST". terra.rice.edu. Retrieved 2016-06-13.
  72. http://www.geoconvention.org/2009abstracts/151.pdf
  73. "Archived copy". Archived from the original on 2013-01-28. Retrieved 2013-01-31.CS1 maint: archived copy as title (link)
  74. "Archived copy". Archived from the original on 2011-07-06. Retrieved 2009-09-25.CS1 maint: archived copy as title (link)
  75. "IGeoS (formerly SIA) geophysical and seismic processing and data analysis". seisweb.usask.ca. Retrieved 2016-06-13.
  76. "Project SEIZMO - A Matlab & Octave Toolbox for Earthquake Seismology". epsc.wustl.edu. Retrieved 2016-06-13.
  77. "Project GISMO - an object-oriented seismic data analysis toolbox for MATLAB". usf.edu. Retrieved 2020-09-11.
  78. Farfour, Mohammed. "MVSPsoft - VSP data processing and interpretation". Retrieved 2019-12-05.
  79. Amosu, Adewale; Sun, Yuefeng (2017). "WheelerLab: An interactive program for sequence stratigraphic analysis of seismic sections, outcrops and well sections and the generation of chronostratigraphic sections and dynamic chronostratigraphic sections". SoftwareX. 6: 19–24. Bibcode:2017SoftX...6...19A. doi:10.1016/j.softx.2016.12.003.
  80. "software.seg.org". software.seg.org. Retrieved 2017-12-04.
  81. "P233 Suite". p223suite.sourceforge.net. Retrieved 2017-12-04.
  82. "Markku Pirttijärvi". wiki.oulu.fi/pages/viewpage.action?pageId=20677906. Retrieved 2017-12-04.
  83. "GALEI". github.com/GeoscienceAustralia/ga-aem.git. Retrieved 2018-03-14.
  84. "openGPR". opengpr.sourceforge.net. Retrieved 2016-06-13.
  85. "MagIC-Py download | SourceForge.net". magic-py.sourceforge.net. Retrieved 2016-06-13.
  86. "Geoid download | SourceForge.net". geoid.sourceforge.net. Retrieved 2016-06-13.
  87. "Project ART at sourceforge.net". artsystem.sourceforge.net. Retrieved 2016-06-13.
  88. "GeoPhysical Calculation Plus Plus download | SourceForge.net". gpcpp.sourceforge.net. Retrieved 2016-06-13.
  89. "Seismic Refraction Tomography download | SourceForge.net". tomoseis.sourceforge.net. Retrieved 2016-06-13.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.