This article is from the Calendars FAQ, by Claus Tondering email@example.com with numerous contributions by others.
This is a big question because there are so many excellent books. At
this point I shall only recommend two books:
Edward M. Reingold & Nachum Dershowitz: "Calendrical Calculations.
The Millennium Edition". Cambridge University Press 2001.
This book contains a lot of information about a huge number of
calendars. As the title indicates, it has a strong emphasis on
algorithms for calendrical calculations, so if you want to use your
computer to compute calendars, this is a great book.
R. W. Bauer: "Calender for Aarene fra 601 til 2200". First published
in 1868. Reprinted 1993 by Dansk Historisk Faellesraad.
Unfortunately, this book is in Danish, but if you can read the
Scandinavian languages, this book will provide you with a wealth of
information, despite its age. Its main strength is a huge collection
of tables of various calendars. It does, however, only describe the