There are two types of essential books to be on your bookshelves. Books to learn from and books to reference.This book is the essential reference. Once you learn Fortran, this is the book to turn to when you need to know the details of the language.I find myself using this book over and over again for my research project. It's short, concise, absolutely accurate and complete, making it the perfect book to have right next to your keyboard.In response to the 1 star review, this is _not_ the book to learn the language from if you know nothing about Fortran, but it would be a serious mistake not to stock your bookshelf with this gem of a book.