Socialism: Utopian and Scientific (Introduction - History) https://marxistleninists.org/M&E/1880/soc-utop/int-hist.htm
LCW: 16: Preface by Progress Publishers https://www.marxists.org/archive/lenin/works/cw/prfv16pp.htm
Eighteenth Congress of the CPSU (B) - 10th of March 1939 http://ciml.250x.com/archive/cpsu/english/1939_march_18_congress_cpsu_b.html