 At the end of 1927 he moved to Moscow, after the nineteenth Universala Kongreso (UK) (World Convention of Esperanto) in Danzig.Among other things, the German veteran Esperantist Konstantin Behnert, who knew Varankin in Tver, tells that after the Danzig UK, Varankin visited Germany without permission and later incautiously mentioned that - with the result that he had to report monthly to register with the police.In 1929 he wrote the textbook "Teorio de Esperanto" (Theory of Esperanto) and a year later also the textbook "Esperanto por laboristoj" (Esperanto for Workers).