«Monty Johnstone: Marx and Engels and the Concept of the Party (1967)». www.marxists.org. Consultado el 28 de agosto de 2024. «190. F. Engels to F.A. Sorge, 24 October 1891, LA, pp.237-8. Carlo Schmid, in his article Ferdinand Lassalle und die Politisierung der deutschen Arbeiterbewegung, in Archiv für Sozialgeschichte (Hanover 1963), III, p.6, notes that it was especially at the Erfurt Congress that the party “officially dissociated itself ideologically from the opinions of Lassalle.”».