The Institute for Slovene emigration of the Centre of Scientific Research of the Slovene Academy of Sciences and Arts keeps a part of the documentary heritage of a significant Slovene politician Etbin Kristan, who after 1912 spent the majority of his life in the USA. Among those materials is a letter of his former socialdemocratic party colleague and one of the first Slovene communists Dragotin Gustinčič from 1938 when Gustinčič was a follower of the international brigades in Spain. In the letter - wholy published - Gustinčič attacks the attitude of the American emigrants in their magazines "Proletarec" towards the Soviet Union and communism in general, and asks Kristan to intervene in order to alter such writing; he also dissaproves the manner of reporting of the mentioned magazines on the civil war in Spain. He stresses the urge for a mutual stand of communists and socialists in the spirit of the solidarity and unity of the Slovene working people in America against the growing fascist danger which threatens Slovenia as well as the whole world. The published document gives an interesting illustration to the history of Slovenes as well in homeland as in emigration.