Smalltalk Literature

[1]  Smalltalk-80, the language and implementation

also known as "the Blue Book" due to its blue cover image.
Written by Adele Goldberg and David Robson, this is the definitive reference for the smalltalk language - a must in every library.
ISBN 0-201-11371-6 Addison Wesley

[2]  Smalltalk-80, the language

also known as "the Purple Book". A new edition of [1] with some updates but also omissions (implementations, as the title suggests).
ISBN ISBN 0-201-13688-0 Addison Wesley

We recommend, having eiher the blue or purple book at hand.

[3]  Smalltalk-80, the interactive programming envronment

written by Adele Goldberg, also known as "the Orange Book". Describes the user interface as in the original Xerox smalltalk implementation. Not up-to-date, but basic concepts of the programming environment are still as described in this book.
ISBN 0-201-11372-4 Addison Wesley

[4]  Smalltalk-80, bits of history words of advice

also known as "the Green Book". Some nice-to-read background information on the history and internals of early smalltalk implementations. Not up-to-date, many new research results make some of the articles obsolete.
ISBN 0-201-11669-3 Addison Wesley

[5]  The design and evaluation of a high performance smalltalk system

written by David Michael Unger, this book describes many techniques which are also used in Smalltalk/X (and other modern smalltalk implementations). Particularly, the description of generation scavenging garbage collection, inline caching and lazy evaluation of contexts are valuable. This is not a book to learn smalltalk, but a good resource for implementation details.
ISBN 0-262-21010-X Mit Press

[6]  X3J20 Ansi Smalltalk Language Standard proposal

[7]  Inside Smalltalk volume 1

written by Wilf R. LaLonde & John R. Pugh.
although being outdated somewhat (since it describes an old version of Smalltalk-80), this book is still a good reference on the smalltalk language and class library. Especially, the basic classes (collections, streams, numeric classes etc.) are described in much detail.
ISBN 0-13-465964-3 Prentice Hall

[8]  Smalltalk - An introduction to Application Development using Visualworks

written by Trevor Hopkins & Bernard Horan.
Recommended - most of it is also valid for Smalltalk/X.
ISBN 0-13-318387-4 Prentice Hall
Now also available as online document. Thanks to the author and the publisher for permitting free publication !
If you can affort the book - go bye it anyway to support the authors !

[9]  The Joy Of Smalltalk

by Ivan Tomek.
Recommended - most of it is also valid for Smalltalk/X.

[10]  Stefane Ducasse's list of free Smalltalk books

many thanks to Stef for maintaining this list, and to the authors & publishers for making these books avalable for free on the net.
Here are some of these books - for those without access to the web:

• A Little Smalltalk by Tim Budd
  Describes Tim Budds "Little Smalltalk" system. Although Little Smalltalk can be regarded as a subset of Smalltalk/X - the text is still worth reading as an introduction to Smalltalks concepts.
  However, any information on object internals, the programming environment or GUI are not valid for Smalltalk/X or other smalltalk systems.

• The Art and Science of Smalltalk by Simon Lewis Uses ViusalWorks for examples - however, most of it also applies unchanged to Smalltalk/X.

• Practical Smalltalk using Smalltalk/V by Dan Shafer & Dean A. Ritz Uses Smalltalk/V, which is somewhat different from VisualWorks and Smalltalk/X.

• Smalltalk and Object Orientation - an Introduction by John Hunt

• Smalltalk by Example by Alex Sharp