Image Licensing

• Wikimedia commons. (2020, October 4). File:Piezoeffekt350px.gif [Gif]. https://commons.wikimedia.org/wiki/File:Piezoeffekt350px.gif
• TED-Ed. (2017, June 20). How to squeeze electricity out of crystals - Ashwini Bharathula [Video]. YouTube. https://www.youtube.com/watch?v=YEJ2qryXcIQ&t=4s
• Stock Videos. (2020, August 6). Football stadium stock video [Video]. YouTube. https://www.youtube.com/watch?v=cT7wGsy32qg