© 2016 Mikkel Kristiansen. Dette værk er under en Creative Commons Navngivelse 4.0 International licens. Besøg http://creativecommons.org/licenses/by/4.0/ for at se en kopi af licensen. Eksternt materiale i form af linkede artikler, opgaver o.lign, se de respektive sider for deres ophavrettigheder.
Public Domain, https://commons.wikimedia.org/w/index.php?curid=465776
By https://www.dvidshub.net/image/43327, Public Domain, https://commons.wikimedia.org/w/index.php?curid=39958429
By Lookang many thanks to author of original simulation = Todd K. Timberlake author of Easy Java Simulation = Francisco Esquembre - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=15643599
By NASA Ames - http://www.nasa.gov/centers/ames/news/2013/pioneer11-40-years.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=25464775
By Tony Webster from Portland, Oregon, United States - Empty Freeway, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=39883581
By RicLaf from Halifax, Canada - Caution! Slippery! (Point Pleasant Park, Halifax NS, June 13 2008), CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=38390338
By Paul Robinson - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2824066
By NASA/MSFC - http://www.nasa.gov/sites/default/files/14-229_0.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=34989964
By Reisio - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=542943