Wetter, J. J. (2011). The impacts of research and development expenditures: The relationship between total factor productivity and U.S. gross domestic product performance. Springer.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Wetter, John J. The Impacts of Research and Development Expenditures: The Relationship Between Total Factor Productivity and U.S. Gross Domestic Product Performance. New York, NY: Springer, 2011.
توثيق جمعية اللغة المعاصرة MLA (الإصدار التاسع)Wetter, John J. The Impacts of Research and Development Expenditures: The Relationship Between Total Factor Productivity and U.S. Gross Domestic Product Performance. Springer, 2011.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.