(RCA, USA 1973, engl.,760 pages)Includes complete specifications and graphs also of the "modern" tubes like 6CA7/EL34,5AR4/GZ34, 6DJ8, 6LF6, 6KG6A/EL509, 6550A, 7027A, 7189, 7591A and the 7868 to name a few. Also includes industrial receiving tubes. This most up to date tube data book is a must for technicians and designers.