You tried going to https://omk12.ru/category/%d0%b0%d0%b1%d0%b8%d1%82%d1%83%d1%80%d0%b8%d0%b5%d0%bd%d1%82%d0%b0%d0%bc/, and it doesn't exist. All is not lost! You can search for what you're looking for.
https://omk12.ru/category/%d0%b0%d0%b1%d0%b8%d1%82%d1%83%d1%80%d0%b8%d0%b5%d0%bd%d1%82%d0%b0%d0%bc/