While visiting a used bookstore a few years ago, I found several textbooks published in the USSR. These books explain the principles of Marxism-Leninism better than anything else I have read. Alas, I cannot find an online version of these texts and the physical copies are pretty rare. I have set up this fediverse blog to transcribe them all in full so there can at least be a searchable version of them. Also in simple HTML format at mltheory.xyz