"Wireless Telegraphy and Telephony" - Swinton, Alan A. Campbell 〈MIEE, FRS, MInstCE, MIMechE〉 (Periodicals Archive Online (PAO), 1920)
http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:q549-1920-069-50-000006
Keywords: LH-LO