Cover image not available
Vol. 4: 2nd ed. (an update & revision to the [unpublished?] first edition by Wally Jackson).
v. 1. To 1885 / by Geoffrey Osborn
v. 4. Gibraltar postal stationery / by E.D. Holmes and R.H. Neville.
OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
Gibraltar : the postal history and postage stamps. ISBN 0950994774. Published by Gibraltar Study Circle in 1995. Publication and catalogue information, links to buy online and reader comments.