The Complete Thief’s Handbook (PHBR2), softback supplement for AD&D 2nd ed.
“Open locks; hide in shadows; move silently; find traps. If you thought that was all a thief was good for, think again. The masters of skulking and skullduggery are a force to be reckoned with. Is anyone or anything safe from a person who might be anywhere, anytime? Learn the thief’s most closely guarded secrets in this devious accessory for the AD&D game.”