APA استشهاد

Ries, A. (1996). Focus: The future of your company depends on it. Harper Business.

استشهاد بنمط شيكاغو

Ries, Al. Focus: The Future of Your Company Depends on It. New York: Harper Business, 1996.

MLA استشهاد

Ries, Al. Focus: The Future of Your Company Depends on It. Harper Business, 1996.