Hagel, J. (2005). The only sustainable edge: Why business strategy depends on productive friction and dynamic specialization. Harvard Business School Press.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Hagel, John. The Only Sustainable Edge: Why Business Strategy Depends on Productive Friction and Dynamic Specialization. Boston, Mass.: Harvard Business School Press, 2005.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Hagel, John. The Only Sustainable Edge: Why Business Strategy Depends on Productive Friction and Dynamic Specialization. Harvard Business School Press, 2005.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.