Book briefing: varied smorgasbord from independent publishers; Black Superstars: Getting Ahead in Today's America, by Bernard Mackler. Buffalo , N.Y.: Conch Magazine Ltd., Publishers (102 Normal Avenue, 14213). $15.

"Much has been said of impoverished Blacks but little of their success." With this observation, clinical psychologist Mackler sets out to chart the routes by which blacks can obtain a position in the American middle class. He focuses mainly on education, business, and sports.

Along the way, he raises some interesting questions: What factors spur a black child to succeed or fail in school? Should blacks strive for success within white-dominated businesses, or seek to develop an alternative black capitalism? Are black athletes still subtly discriminated against?

Unfortunately, Mackler's development of his theme is uneven. At some points he confines himself to a review of previous research; at others he unleashes torrents of unsupported generalizations. Although he provides a few fresh insights and cites a range of opini on, as a whole his work lacks coherence.