A good short book on use cases is Schneider and Winters (1998). Its current printing uses the UML 1.1 relationshipsuses and extendsbut it remains the best book I've seen on how to apply use cases. My other favorite recommendation is the set of papers at Alistair Cock-burn's Web site: <http://members.aol.com/acockburn>.
Ivar Jacobson's first book (1994) is the book that started the ball rolling, but it's rather dated now. Jacobson's follow-up book (1995) is still useful for its accent on business use cases.