Wireless Step By Step – Dictron 1928The Outline of Wireless – R Stranger 1931Simultaneous Telephony and Telegraphy Rhoads – Casper 1928Robison’s Manual of Radio Telegraphy and Telephony – Robison 5th ED 1919Radio For Everyone – Lescarboura 1924Gernsbacks Radio Encyclopedia – Gernsback 1927Handbook for Wireless Telegraphists Hawkhead – Dowsett 1925