Arjen Markus This classical, even seminal book on testing techniques concentrates on the whitebox approach. A heavy volume stuffed with details, but a must for any one who takes the job seriously.
Bibliographical details:
Boris Beizer, Software Testing Techniques, Van Nostrand Reinhold, New York, second edition, 1990
As a personal note: This was the book that told me Tcl exists and how wonderful it is in a testing context.