APL in Practice: What You Need to Know, to Install
By Allen J. Rose; John Wiley & Sons, 1980, ISBN 0471082759. Textbook. [Amazon.com]
APL Is Easy
By STSC, Inc.; John Wiley & Sons, 1987, ISBN 047185882X. Beginner's tutorial, business oriented. [Amazon.com]
APL Programming and Computer Techniques
By Harry J. Katzan; Van Nostrand Reinhold, 1970, ISBN 0442242514. [Amazon.com]
APL With a Mathematical Accent
By Clifford A. Reiter, William R. Jones; CRC Press, 1990, ISBN 0534128645. Introduces APL; suitable as main text for courses using computers to solve mathematical problems, or for mathematical experimentation. [Amazon.com]
APL, an Interactive Approach
By Leonard Gilman; Krieger Publishing, 1991, ISBN 0894646575. Classic, clear introduction to APL. [Amazon.com]
APL/360: An Interactive Approach
By Leonard Gilman; John Wiley & Sons, (date?), ISBN 0471300209. [Amazon.com]
APL2 at a Glance
By James A. Brown, Sandra Pakin, Raymond P. Polivka; Prentice Hall, 1988, ISBN 0130386707. Introduces APL2, an IBM dialect that runs on Windows; IBM OS/2, RS6000, mainframes. [Amazon.com]
APL2 in Depth
By Norman D. Thomson, R.P. Polivka; Springer Verlag, 1995, ISBN 0387942130. For extant APL users who want to gain APL2 skills. [Amazon.com]
APL: A Short Course
By Sandra Pakin; Prentice Hall, 1973, ISBN 0130388777. Introduction. [Amazon.com]
APL: The Language and Its Usage
By Raymond Peter, R.P. Polivka; Prentice Hall, 1975, ISBN 0130388858. Textbook. [Amazon.com]
Invitation to APL for the IBM-PC
By Lawrence L. McNitt; Petrocelli Books, 1988, ISBN 0894332678. Treats some personal computer and x86 issues. [Amazon.com]
Learning and Applying APL
By B. Legrand; John Wiley & Sons, 1984, ISBN 0060442433. [Amazon.com]
Learning APL: An Array Processing Language
By James Mason; John Wiley & Sons, 1985, ISBN 0471603392. Introductory paperback. [Amazon.com]