As a result of orthographic transcription from the Russian, Moissey Kogan’s first name appears in the primary and secondary sources in many variant forms. His surname is almost exclusively spelt Kogan, occasionally Cogan. The choice of spelling for his first name appears to depend either on the conventions of the country concerned or on personal preference. Variants include Moissey, Moïse, Moïssy, Moissi, Moyssey, Moishe, Moisey, Moisej, Moishé, Moisje, Moisei, and several others.
Kogan himself used different versions of his name at different times. In the main, he simply signed his letters, ‘Kogan’; to his intimates, he was Micha.