The technique of unprofitable telegraph (in elementary presentation)

Cretan, M.The technique of unprofitable telegraph (in elementary presentation): a manual for radio engineers.- 3rd ed.-Sank-Petersburg: ed.K.L.Ricker, 1914. -[2], 85 p.: il., table .. -Ex.: Without region., With a handle.litter..1. The people (collection).Electronic copy source: PBPlace of storage of the original: the Central Museum of Communications named after A.S.Popova