https://proshkolu.ru/user/sgibnev/
https://proshkolu.ru/user/sgibnev/blog/

2019
Sgibnev - Geometry on Movable Drawings ru
    https://chitatel.by/catalog/book/1235989
    329FE11E971D58CE8BEC861976E7D724
2018
About introducing Letters in Algebra
    https://www.youtube.com/watch?v=hRcED4U0kqg

2015
Sgibnev - Numbers Divisability and Simple Numbers 3rd ed ru
    DA5A1E66AE46FA024E746B521F1A3C33
Sgibnev - Research Problems for Beginners ru

????
Sgibnev - Geometry Helps to Algebra
    http://geometry.ru/kruzhki/big/alg_geo.pdf