Lee, Marshall, Bookmaking.
"Bookmaking," by Marshall Lee, is also a very instructive guide. Third edition, revised and brought up to date for the electronic age, is in preparation, and due for publication in 1997 by W. W. Norton.

Rice, Stanley, Book Design: Systematic Aspects.
I have also found Stanley Rice's "Book Design: Systematic Aspects" equally helpful; but it, too, is getting long in the teeth. It was published by Xerox in 1978.

Tschichold, Jan, The Form of the Book.
Hartley & Marks, 1992
A fine collection covering some of Tschichold's writings over a quarter century. Perhaps less broad and thorough than Bringhurst's book, probably because it's a collection of essays. I found it very illuminating.

Dair, Carl. Design with Type.
Toronto, Buffalo NY, University of Toronto Press, 1967, 1998

Dair, Carl, Type by Design.

Kirshenbaum, Sandra et al - editors, Best of Fine Print on Type and Typography

Tracy, Walter, Letters of Credit.

Burns, Aaron, Typography.
New York, 1961, Reinhold
Oout of Print
A classic book by a classic typographer.

Spiekermann, Erik, Rhyme & Reason: A Typographic Novel.
Berlin, 1987, H. Berthold AG
ISBN 3-9800722-5-8
Another classic by another classic.

Chappell, Warren, A Short History of the Printed Word.
New York, Alfred A Knopf, 1970.
2nd Revised & updated edition, Robert Bringhurst, contributor
Hartley & Marks, 2000
ISBN: 0881791547
A thoroughly enjoyable read on the people, places, and things that make up the history of type and publishing. Warren Chappell's book was revised and appended by noted author Robert Bringhurst and this book is the perfect complement to Bringhurst's own "Elements of Typographic Style". ... And anything else by this author.

Dowding, Geoffrey, Finer Points in the Spacing & Arrangement of Type.
(Original issue: London, Wace & Co. 1957, 1966), Pt Roberts, WA: Hartley & Marks, Pubs. 1995.
ISBN: 0-88179-119-9

Wilson, Adrian, The Design of Books.
(first issue, 1967)
San Francisco: Chronicle books, 1993.
ISBN: 0-8118-0304-X

Gill, Eric, An Essay on Typography.
Available in the United States as a paperback reprint published by David Godine
ISBN: 0-87923-950-6

McClean, Ruari, Typographers on Type : An Illustrated Anthology from William Morris to the Present Day.
The selections are too short IMO but good anyway -- can point to other stuff.

Seybold, Jonathan, Primer for Computer Typesetting.
Not sure if it's still available. It is a detailed and lucid description of the logic at work behind the electronics.

Hurlburt, Allen. Publication Design: A guide to page layout, typography, format and style.
Van Nostrand Reinhold Company, 1976 and 1971.

Hurlburt, Allen. The Grid: A modular system for the design and production of newspapers, magazines and books.
John Wiley & Sons, Inc., 1978.

Swann, Alan. How to Understand and Use Grids.
Quarto Publishing plc, 1989.

Thinking in Type: The Practical Philosophy of Typography
by Alex W. White

Stop Stealing Sheep & Find Out How Type Works
by Erick Spiekerman

Thinking with Type: A Critical Guide for Designers, Writers, Editors, & Students by Ellen Lupton