PORTER MICHAEL E. (1980). COMPETITIVE STRATEGY: TECHNIQUES FOR ANALYZING INDUSTRIES AND COMPETITORS. FREE PRESS.
Chicago Style aipamenaPORTER MICHAEL E. COMPETITIVE STRATEGY: TECHNIQUES FOR ANALYZING INDUSTRIES AND COMPETITORS. NEW YORK: FREE PRESS, 1980.
MLA aipamenaPORTER MICHAEL E. COMPETITIVE STRATEGY: TECHNIQUES FOR ANALYZING INDUSTRIES AND COMPETITORS. FREE PRESS, 1980.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.