Não informado. (1949). Abstracts of recent published material on soil and water conservation. Agricultural Research Service, Soil and Water Conservation Division.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Não informado. Abstracts of Recent Published Material on Soil and Water Conservation. Washington: Agricultural Research Service, Soil and Water Conservation Division, 1949.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Não informado. Abstracts of Recent Published Material on Soil and Water Conservation. Agricultural Research Service, Soil and Water Conservation Division, 1949.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.