Shorthand for BOOK Structure and Interpretation of Computer Programs. This book is one of a small handful commonly referenced when someone asks for a Scheme reference book. Beyond that it is a very good introduction into computational concepts in general.
Abelson, Harold
Structure and interpretation of computer programs / Harold Abelson
and Gerald Jay Sussman, with Julie Sussman. -- 2nd ed.
p. cm. -- (Electrical engineering and computer science
series)
Includes bibliographical references and index.
ISBN 0-262-01153-0 (MIT Press hardcover)
ISBN 0-262-51087-1 (MIT Press paperback)
ISBN 0-07-000484-6 (McGraw-Hill hardcover) program language) I. Sussman, Gerald Jay. II. Sussman, Julie. III. Title. IV. Series: MIT electrical engineering and computer science series. QA76.6.A255 1996 005.13'3 -- dc20 96-17756 Fourth printing, 1999
Full text at http://mitpress.mit.edu/sicp/full-text/book/book.html
It's also a classic of language theory, quite apparent from its use of Scheme for exposition; in fact, CL hears more recommendations of it as a tutorial on programming principles than for Scheme. For the latter role, the usual candidates are The Little Schemer, ...