On the Ultimate Edition:
- Victor J. Katz, Mathematical Reviews
It retains all the features that made the first edition ... such a
wonderful resource, while adding much new material ... If you are
at all interested in time and calendars, this book must find a place
on your desk.
On the third edition:
- John Cook, MAA Reviews
the reliance on software makes the book harder to skim, it makes the
book far more precise. If you really want to know how to make
calculations according to any of the calendar systems in the book, you
need to handle a lot of details, and software makes these details
explicit. (And testable. I would have more confidence in the
correctness of software than purely prose descriptions because
presumably the former has been tested, and would be easier to test if
I were to verify it myself.) Software functions can refer to each
other in far more precise ways than text references.
- 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.
On the Millennium Edition:
- 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
- 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.
On the first edition:
- 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
- ...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
- 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
- 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
- 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
...une œuvre considérable sur les calculs calendaires.