First International Archive http://ciml.250x.com/archive/international1/english/french_letter_to_german_social-democracy_paris_commune.html
Doctoral Dissertation of Karl Marx — Part II, Chapter 3 https://marxistleninists.org/M&E/1841/dr-theses/ch06.htm
Lenin: On the 'Nature' of the Russian Revolution https://www.marxists.org/archive/lenin/works/1908/mar/26b.htm