Eiffel, P. (February 1938). "A Letter from Mexico". Spark. 1 (1): 35–38. Retrieved 6 June 2021. In the letter, Kirchhoff mentions his support for a letter by the "Italian Left Fraction of Communism" that the RWL had previously published; this appeared in the October 1937 issue of the RWL's Fighting Worker. He also addresses the allegations made by the Mexican Trotskyists.
