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
Doctoral Dissertation of Karl Marx — Foreword https://marxistleninists.org/M&E/1841/dr-theses/foreword.htm
Reviews from the Neue Rheinische Zeitung Politisch-okonomische http://hiaw.org/defcon6/works/1850/02/simon.html