“Parts of a Circle”, posted at mathcaptain.com, Oct. 22, 2012, [site visited Oct. 2, 2017]. Available from Internet: <http://web.archive.org/web/20121022020149/http://www.mathcaptain.com/geometry/parts-of-a-circle.html>. |
“Getting started in figure drawing”, posted at learnhowtodraw.com, Feb. 15, 2015, [site visited Oct. 2, 2017]. Available from Internet: <https://web.archive.org/web/20010202194400/http://www.learnhowtodraw.com/freehandsketching.html>. |
Kepler's Laws Tutorial, posted at tobyrsmith.github.io, Jan. 20, 2016, [site visited Sep. 29, 2017]. Available from Internet: <https://web.archive.org/web/20160120165104/http://tobyrsmith.github.io/Astro150/Tutorials/Kepler>. |
Fesenmaier, Kimm, “Wandering Jupiter accounts for our unusual solar system”, posted at phys.org, Mar. 23, 2015, [site visited Sep. 29, 2017]. Available from Internet: <https://phys.org/news/2015-03-jupiter-accounts-unusual-solar.html>. |
“Colors Circles GIF” Jan. 3, 2014, posted at giphy.com, [site visited Feb. 19, 2019]. https://giphy.com/gifs/psychedelic-colors-circles-t1dPkqBqlHcfS. |
“circle-pulses.mi_.gif” Aug. 14, 2011, posted at tommoody.us, [site visited Feb. 19, 2019]. https://tommoody.us/images/aug11/circle-pulses.mi_.gif. |
“SFSN-Circle.gif” May 2016, posted at nhsfforthvalley.com, [site visited Feb. 19, 2019]. https://nhsforthvalley.com/wp-content/uploads/2016/05/SFSN-Circle.gif. |
Whyte, Dave, “Circle wave” Aug. 23, 2014, posted at dribbble.com, [site visited Feb. 19, 2019]. https://dribbble.com/shots/1696376-Circle-wave. |