Richard T. Snodgrass, Developing Time-Oriented Database Applications in SQL, Morgan Kaufmann Publishers, Inc., San Francisco, July, 1999, 504+xxiii pages. This book is out of print. Here it is in PDF (5MB) (which looks a little fuzzy but prints fine, except for pages 30-31, which are here) and its associated CD-ROM in zip (59MB) (available only on DVD) or gzipped tar (57MB) (available only on DVD) formats.