Audio Books Co., P.O. Box 9100, Van Nuys, Calif. 91409, (213) 799-4139. Popular novels, plays, poetry, etc. Rentals: $4.95 to $8.95 for 30 days, sent in post-paid return mailers. Sales: $9.95 for 2-cassette set. Catalog contains over 100 titles.

Audio-Forum, Jeffrey Norton Publishers, 145 E. 49th St., New York, N.Y. 10017, (212) 753-1783. Wide range of titles including the classics, letters, arts, business, foreign language, literary criticism. $10.95 and up. Catalog available.

Books on Tape, P.O. Box 7900, Newport Beach, Calif. 92660, (800) 854-6758. Novels available, rental only, $6.50 to $16.50 for 30 days. Foreign language, purchase only. Catalog available.

Caedmon, 1995 Broadway, New York, N.Y. 10023, (800) 223-0420. Wide range of titles: classics, quality novels, plays, poetry, literary and historical figures "Spoken Word" series. $8.98 and up. Catalogs.

Folkways Records, 43 W. 61st St., New York, N.Y. 10023, (212) 586-7260. "Spoken Word," literature, instructional, foreign languages. $9.95 and up. Catalog available.

Listening Library, P.O. Box L, Old Greenwich, Conn. 06870,(203) 637-3616. Language arts, all aspects of language; $8.95 for single, $17.90 for 2-cassette sets. Catalog.

Newstrack, Executive Tape Service, Box 1178, Englewood, Colo. 80150, (800) 525-8389. Bimonthly subscription, readings from current publications. $195 a year.

"Sound of Business," Harris Trust & Savings Bank, 6 East P.O. 755, Chicago, Ill. 60690,(312) 461-7631. Business, economics; aimed at middle- and high-level corporate managers. Subscription $100 a year for 12 half-hour cassettes.

Washington Audio Journal, Broadcast Center, U.S. Chamber of Commerce, 1615 H St. NW, Washington, D.C. 20062, 659-6238. Bimonthly business cassette program, $150 a year.