Willingham, W. F. (1983). Army engineers and the development of Oregon: A history of the Portland District, U.S. Army Corps of Engineers. U.S. Army Corps of Engineers.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Willingham, William F. Army Engineers and the Development of Oregon: A History of the Portland District, U.S. Army Corps of Engineers. [Washington, D.C.?: U.S. Army Corps of Engineers, 1983.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Willingham, William F. Army Engineers and the Development of Oregon: A History of the Portland District, U.S. Army Corps of Engineers. U.S. Army Corps of Engineers, 1983.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.