Ries, A. (1996). Focus: The future of your company depends on it. New York: HarperBusiness.
استشهاد بنمط شيكاغوRies, Al. Focus: The Future of Your Company Depends On It. New York: HarperBusiness, 1996.
MLA استشهادRies, Al. Focus: The Future of Your Company Depends On It. New York: HarperBusiness, 1996.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.