Calendrical Calculations
"Because years, months, and days don't mesh simply, calendar making has been a challenge throughout history. Dershowitz and Reingold's compendium, here in its third edition, has already established itself as the definitive reference on calendrical structures. Their manual displays conversions between all the major calendar systems as well as between many fascinating schemes from bygone civilizations."  Owen Gingerich, Harvard-Smithsonian Center for Astrophysics"One of the most fascinating books I've read all year. Takes chronology into the computer age with impressive erudition and elan. Just finding out what the calendar rules are is usually close to impossible; Calendrical Calculations tell you how to use them too. A must for everyone who worries about days, months, years - and why they never quite fit."  Ian Stewart"A good, comprehensive documentation of software for calculating dates on very many calendars."  P. Kenneth Seidlmann, Director of Astronomy, U.S. Naval Observatory"One of those rare books that is both an authoritative reference source and a fun read."  Danny Hillis"The book is a definitive account of the world's major calendars and how to use them. It will be of interest not only to mathematicians, but also to historians and laymen. The authors are to be congratulated on a splendid research job."  Martin Gardner"This book must surely become the standard work on calendar conversions. No historian, chronologist, or recreational mathematician should be without it."  E.G. Richards, Nature