Não informado. (1909). Circular of the Department of Agriculture, Trinidad and Tobago. Circular of the Department of Agriculture.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Não informado. Circular of the Department of Agriculture, Trinidad and Tobago. Port of Spain: Circular of the Department of Agriculture, 1909.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Não informado. Circular of the Department of Agriculture, Trinidad and Tobago. Circular of the Department of Agriculture, 1909.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.