Cassell's German Dictionary: German–English/English–German (New York: Cassell and Co. Ltd., ©1971)

Cuthbertson's Verb Wheel (Lexington, MA: D.C. Heath, ©1933)
gives conjugations of irregular verbs.

English Grammar for Students of German, 3rd edition (Ann Arbor, MI: The Olivia and Hill Press, ©1994)
"study guide for those learning German" by Cecile Zorach and Charlotte Melin; designed to be an accompaniment to any textbook, this guide offers simple explanations of English grammar structures (i.e., parts of speech, word functions, grammatical concepts) by answering basic questions (ex: What is gender? What are relative pronouns? etc.); uses examples, charts, step-by-step instruction,s and short practice exercises (with answer key) to identify similarities and differences between English and German; 176 pages.

501 German Verbs, 2nd ed. by Henry Strutz (Hauppauge, NY: Barron's Educational Services, Inc., ©1990).

Der Gimmick Gesprochenes Deutsch by Adrienne Penner (New York: W.W. Norton Co., Inc., ©1977)
a text for vocabulary building designed to help the student "learn the language as it is actually spoken"; includes idiomatic and colloquial/slang expressions.

A Practical Guide to the Teaching Of German by Wilga Rivers, Kathleen Mitchell Dell'Orto, and Vincent Dell'Orto (New York: Oxford University Press, ©1975)
one in a series of practical guides for teaching foreign languages in high school or at the undergraduate level; includes theoretical discussions of and practical applications for oral communication, pronunciation, grammar instruction, listening and reading comprehension, and writing; 346 pages.