https://learningstatisticswithr.com/
https://www.cut-the-knot.org/manifesto/index.shtml
https://www.illustrativemathematics.org/
https://github.com/benweet/stackedit
https://www.math.hmc.edu/funfacts/
https://cindyjs.org/gallery/main/
https://github.com/enjalot/algovis