In the distribution of the Olson database, the Theory file mentions "Calendrical Calculations, Millennium Edition" from 2001. There is a new edition of the book available now: Calendrical Calculations, 3rd Edn. 2008 Nachum Dershowitz, Edward M Reingold Cambridge University Press ISBN 978-0-521-88540-9 (hardback) ISBN 978-0-521-70238-6 (paperback) Web sites: http://www.cambridge.org/9780521885409 http://www.calendarists.org/ (Note: the latter web site does not mention the 3rd Edn as of 2008-01-06; I'm not clear whether it will be updated to do so. It does have an extensive set of errata for CCME on it.) -- Jonathan Leffler <jonathan.leffler@gmail.com> #include <disclaimer.h> Guardian of DBD::Informix - v2007.0914 - http://dbi.perl.org "Blessed are we who can laugh at ourselves, for we shall never cease to be amused."