Nowadays all serious testing, expecially of high-integrity systems, uses test coverage measurement to control the testing process. Hetzel was among the first to recognise the value of such measurement and write about coverage based testing from the managerial perspective. Though first published some years ago, his text is wearing well.
As a consulting software engineer, I often have clients ask me about how they should manage testing. In almost every case, I advise them to start by reading Hetzel's book. His style is engaging and he gets across the essentials without getting bogged down in details. For me Hetzel says more and in fewer and clearer words than Black's "Managing the Testing Process".
That said, however, IMO there remains a gap in the market for a book that integrates both the technical and managerial aspects of software testing. Until someone writes one, I recommend Hetzel, Jorgensen's "Software Testing: A Craftsman's Approach" and Beizer's "Software Testing Techniques" to cover both the managerial and technical ground.