C. Díaz Hernández, «KUMPF, Fritz: Probleme der Dialektik in Lenins Imperialismus-Analyse»., Logos, vol. 4, p. 85, gen. 1969, Consultato: lug. 15, 2026. Disponibile su: https://revistas.ucm.es/index.php/ASEM/article/view/ASEM6969110085A