- 1R. P. G. Denman
Electrical Communication II : Wireless Telegraphy and Telephony
1925; 72 S. : Ill., graph. Darst.
Telegraph; Telefon; Katalog - 2R. P. G. Denman
Electrical Communication : Line Telegraphy and Telephony with descriptive and historical notes and illustrations
1926; 55 S. : Ill., graph. Darst.
Telegraph; Telefon; Katalog