"Karl Marx I" Progress, May 1883, pp. 288-294, and "Karl Marx II" Progress, June 1883, pp. 362-366; both articles are online: https://www.marxists.org/archive/eleanor-marx/1883/06/karl-marx.htm, A Bibliography of Female Economic Thought up to 1940. Ed. By Kirsten Madden, Michele Pujol, Janet Seitz. Routledge, 2004, pp. 26-7.
Royle (1980), op. cit., p. 33., Tsuzuki (Berlin: 1981), S.147.; See Wearing, J. P. "Archer, William (1856–1924), theatre critic and journalist". Oxford Dictionary of National Biography. 03. Oxford University Press. Date of access 28 August 2022
Edward Aveling an Ernst Haeckel, London, 29. Oktober 1880 (Signatur: EHA Jena, A 8436). The letter is readable online at https://haeckel-briefwechsel-projekt.uni-jena.de/de/document/b_8436 as part of the Ernst Haeckel Online Briefedition, funded by the Union of the German Academies of Sciences and supervised by the German Academy of Natural Scientists Leopoldina - National Academy of Sciences.
