2. Izquierdo, Manuel P. "A organização em Marx e Engels." pp. 8-11, 13. [other title:"La organización en Marx y Engels."]

2. Izquierdo, Manuel P. "A organização em Marx e Engels." pp. 8-11, 13. [other title:"La organización en Marx y Engels."], Box: 27. Eduardo Sarno Collection of Leftist Movements in Brazil, 2002-03. Benson Latin American Collection, The University of Texas at Austin. https://archives.lib.utexas.edu/repositories/4/archival_objects/375903 Accessed September 26, 2026.