Não informado. Virginia agricultural economics. Virginia Polytechnic Institute, Department of Agricultural Economics and Rural Sociology.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Não informado. Virginia Agricultural Economics. Blacksburg, Va: Virginia Polytechnic Institute, Department of Agricultural Economics and Rural Sociology.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Não informado. Virginia Agricultural Economics. Virginia Polytechnic Institute, Department of Agricultural Economics and Rural Sociology.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.