Bedford, Bruce L books & textbook
Challenge underground (Speleologia)
G. Allen & Unwin /1975T Hardcover / 192 Pages
isbn-10: 0914264168 / isbn-13: 9780914264163
Cave Diving: The Cave Diving Group Manual
Imprint unknown /1990-05-25 Paperback / 268 Pages
isbn-10: 0905903145 / isbn-13: 9780905903149
