Claus Tøndering –
(Please include the word “calendar” in the subject line)

Frequently Asked Questions about this FAQ

This chapter does not answer questions about calendars. Instead it answers questions that I am often asked about this FAQ.

Why doesn’t the FAQ describe calendar X?

I am frequently asked to add a chapter describing the Japanese calendar, the Ethiopian calendar, the Hindu calendar, etc.

But I have to stop somewhere. I have discovered that the more calendars I include in the FAQ, the more difficult it becomes to ensure that the information given is correct. I want to work on the quality rather than the quantity of information in this document. It is therefore not likely that other calendars will be added in the near future.

Why doesn’t the FAQ contain information X?

Obviously, I cannot include everything. So I have to prioritize. The things that are most likely to be omitted from the FAQ are:

  • Information that is relevant to a single country only.
  • Views that are controversial and not supported by recognized authorities.

Why don’t you reply to my e-mail?

I try to reply to all the e-mail I receive. But occasionally the amount of mail I receive is so large that I have to ignore some letters. If this has caused your letter to be lost, I apologize.

But please don’t let this stop you from writing to me. I enjoy receiving letters, even if I can’t answer them all.

How do I know that I can trust your information?

I have tried to be accurate in everything I have described. If you are unsure about something that I write, I suggest that you try to verify the information yourself. If you come across a recognized authority that contradicts something that I’ve written, please let me know.

Can you recommend any good books about calendars?

This is a big question because there are so many excellent books. At this point I shall only recommend three books:

  • Edward M. Reingold & Nachum Dershowitz: Calendrical Calculations. Third Edition. Cambridge University Press 2008. ISBN 978-0-521-70238-6
  • 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.

  • Bonnie Blackburn & Leofranc Holford-Strevens: The Oxford Companion to the Year. Oxford University Press 1999. ISBN 0-19-214231-3.
  • A very thorough (900+ pages) book about the history of calendars. The book includes a large collections about customs related to each day of the year.

    Finally, I have myself written a book:

  • Claus Tøndering: Julius og Gregor. 2007. ISBN 978-87-92032-58-4.
  • Unfortunately, this book is in Danish, but if you can read the Scandinavian languages, this is a useful handbook. One of its main strengths is a large collection of tables of various calendars.

Do you know a web site where I can find information about X?

Probably not.

Good places to start your calendar search include: