Porter, Michael E., 1947- Competitive Strategy : techniques for analyzing industries and competitors / Michael E. Porter. - New York : Free Press, c1980. - xx, 396 p. : ill. ; 25 cm. Includes index. Bibliography: p. 383-387. ISBN: 0029253608 Subjects--Topical Terms: Competition.Industrial management. Dewey Class. No.: 658.4 / POR