Duff, R. W. (2010). Retirement breakthrough: The safe, secure way to guaranteed income you can't outlive-- in any economy. Greenleaf Book Group Press.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Duff, Richard W. Retirement Breakthrough: The Safe, Secure Way to Guaranteed Income You Can't Outlive-- in Any Economy. Austin, Texas: Greenleaf Book Group Press, 2010.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Duff, Richard W. Retirement Breakthrough: The Safe, Secure Way to Guaranteed Income You Can't Outlive-- in Any Economy. Greenleaf Book Group Press, 2010.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.