A complete textbook for students, instructors and advanced divers. Illustrated in B/W. Indexed. Includes pamphlet of explanation of tank/reserve valve charts. Owners name neatly inscribed on cover sheet. No other marks. Pictorial wraps. VVG. (135 Pgs.)AUTHOR: Joe Strykowski PUBLISHER: Dacor Corp. ISBN: 74-31233 YEAR: 1974 FORMAT: Softcover EDITION: Fourth Revised Ed.