Marx & Engels: Chapter Three of German Ideology https://marxistleninists.org/M&E/1845/german-ideology/ch03.htm
Footnotrs: Revelations of the Diplomatic History of the 18th Century http://hiaw.org/defcon6/works/1857/russia/notes.html
Lenin: From the Defensive to the Offensive https://www.marxists.org/archive/lenin/works/1905/sep/26e.htm
True Socialism by Karl Marx and Frederick Engels https://marxistleninists.org/M&E/1845/german-ideology/ch04a.htm