**Owen Gingerich:**- Because years, moonths, and days don't mesh simply, calendar making has been a challenge throughout history. Reingold and Dershowitz'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.

**P. Kenneth Seidelmann:**- A good, comprehensive documentation of software for calculating dates on very many calendars.

**David N. Smith (author of***Concepts of Object-Oriented Programming*and*IBM Smalltalk: The Language*)*Amazon.com*(20 Apr 2001):- Super! Better than the first edition: give it 6 stars.

*American Scientist*(Jan-Feb 2002):- Would you like to know the date of Good Friday in 1776, or when Ramadan will start in 2003? ... With this book on your shelf, you'll never miss out on a date.

**V. V. Raman,***Choice*(1 Apr 2002):- Outstanding Title! Calendars are a synthesis of culture and science, of tradition and astronomy. As there are many cultures and many traditions, there are also many calendars. But since there is only one science, and one astronomy, the various calendars of the human family must be interconnected. This very valuable book enables us to establish those interconnections, though its title has a word that may not be found in all dictionaries. Calculations to pass from one system to another are very complex, but they can be tracked down using computers and algorithms; this is what the authors have done. For the book to be intelligible, let alone useful, some technical background in astronomy, computers, and calculations is indispensable. Reingold and Dershowitz not only have accomplished something of immense value to those engaged in calendrical creations, but they have also brought together between the covers of a single volume 20 calendars, current and historical, of universal significance. A true labor of love, this cultural service to humanity should be in every library of the world.

**William H. MacIntosh,***Computing Reviews*(May 2002):- A fascinating book.

**Manfred Kudlek,***Zentralblatt MATH*(0894.01023):- Since Ginzel's
*Handbuch*this is the most extensive and detailed publication on calendar systems.

**Sacha Stern, author of***Calendar and Commmunity*(10 Sep 2002):- A genuine tour de force.

**Ian Stewart:**- 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*tells you how to use them too. A must for everyone who worries about days, months, years and why they never quite fit.

**Martin Gardner:**- 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.

**E. G. Richards,***Nature*(1 Jan 1998):- ...this book must surely become the standard work on calendar conversions. No historian, chronologist or recreational mathematician should be without it.

**Antonio F. Rañada,***European Journal of Physics*(Mar 1998):- ...a really attractive book, not only for specialists such as mathematicians, astronomers or computer scientists, but also for historians or for any person interested in the cultural aspects of science. I doubt that such a clear exposition of the mathematical structure of the calendar rules necessary to move from one to another of these fourteen calendars could be found elsewhere. ...this is a splendid book, of interest to astronomers and computer scientists, and to anyone concerned with the role of science in the cultural evolution of mankind.

**A. A. Mullin,***Computing Reviews*(May 1998):- I recommend this book highly both as a software resource for students and teachers of computer science and to general readers interested in the history and science of the world's main calendars.

**V. J. Katz,***Mathematics Reviews*(July 1998):- If you are at all interested in in how we deal with time, you must have this exceptional book.

**F. Richard Stephenson,***Astronomy Now*(Aug 1998):- This book provides a comprehensive numerical treatment of a wide variety of calendars and much originality and effort has gone into its production. ...suitably equipped readers should find this a valuable reference work.

**I. J. Lund,***Amazon.com*(23 Aug 1998):- Excellent source for calculations of many world calendars.... The explanation of the algorithms and descriptions of the exact details of calculation of calendars is extremely clear and well researched.

**David M. F. Chapman,***Journal of the Royal Astronomical Society of Canada*(Aug 1998):-
Anyone interested in chronology should acquire
*Calendrical Calculations*.

**A reader from USA,***Amazon.com*(2 Oct 1998):- ...this is simply the best reference for Calendrical Calculations in the computer age. No other book comes close in terms of completeness and thoroughness. A must-have for anyone interested in this area of history or programming.

**D. McCarthy,***ISIS*(Dec 1998):- The work is attractively produced and well written, in a crisp and lucid style, its earnest content lightened by touches of humor and details of history that communicate most effectively the authors' enthusiasm for and knowledge of their subject. ...this book supplies the essential tools to enable us to proceed cogently and efficiently toward correlation of all these derivative calendrical systems, and Dershowitz and Reingold are to be congratulated on making strides toward this goal.

**Danny Hillis,***Amazon.com*(18 Jan 1999):- Just what I needed. In the course of building a 10,000 year clock I needed to know a lot of obscure details about various calendar systems. Calendrical Calculations not only answered all my questions, but it also introduced me to a lot of interesting information that I never would have thought to ask about. It is one of those rare books that is both an authoritative reference source and a fun read.

**R. Poole,***British Journal for the History of Science*(Mar 1999):- What a wizard wheeze! ...Dershowitz and Reingold...have devoted a large part of their joint lives to a task which anyone in their right mind will be glad someone else did. ...As the millennium approaches, books purporting to explain the calendar are appearing like cactus flowers after a storm, full of secondhand errors, third-order simplifications, and outright myths. Dershowitz and Reingold, by contrast, have worked at source and confronted every difficulty. Their book can be recommended as a pithy and reliable distillation of all the world's main calendars. As a bare work of reference, it leads the market.

**A reader from Munich, Germany,***Amazon.com*(28 Apr 1999):- ...highly readable and reliable description of many calendars. The book explains the structure of 14 calendars, and gives easily comprehensible formulae for the conversion of a date in any of these calendars into a day count, and back to the calendar date. It also includes many holidays for these calendars. ...the focus is on a lucid, correct, and complete exposition of their functional principles. Extensive bibliographic references are given to the primary sources for each calendar. A highlight is the complete specification of several calendars depending on fairly precise timings of astronomical phenomena (Chinese calendar and some Hindu religious calendars). ...The formulae are designed so that it is easy to incorporate them into code written in the programming language of your choice. This use is further supported by a set of test dates in an appendix. Another appendix lists an example implementation of all the formulae, in the programming language Common Lisp. This code (intended for personal use) can also be downloaded from the internet. But this book is much more than a collection of programming recipes for many calendars -- it makes you understand the structure of those calendars. Ambitious readers can even find the data and the methods to construct their own calendrical formulae. This book is a must for everybody wanting reliable and highly readable information on the functional principles of the world's calendars.

**William Wynne Willson,***The Mathematical Gazette*(Mar 1999):- This is a fascinating book to dip into, as well as being a powerful reference work assembling a rich collection of historical, astronomical and computational `calendar' facts. If you have funds set aside for coping with the millennium bug why not spend a little of them on a copy?

**Giuseppe Gatto,***Calendrier et informatique*(Jul 2000):- ...une œuvre considérable sur les calculs calendaires.

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