The Blue Book is a book that used to be called the White Book when it was blue and then it turned into a white book and was called the Blue Book and has been called the Blue Book ever since even though it is neither blue nor white these days and, in fact, it's not even a proper book anymore but a PDF file. The Blue Book is a PDF file with useful mathematical and physical equations and constants. Go to the Blue Book now(pdf, 550 kB).
