Great Northern Railway Company (U.S.). (1921). Zone of plenty: Minnesota, North Dakota, Montana, Washington, Oregon, Idaho. Great Northern Railway.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Great Northern Railway Company (U.S.). Zone of Plenty: Minnesota, North Dakota, Montana, Washington, Oregon, Idaho. [Saint Paul, Minn.]: Great Northern Railway, 1921.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Great Northern Railway Company (U.S.). Zone of Plenty: Minnesota, North Dakota, Montana, Washington, Oregon, Idaho. Great Northern Railway, 1921.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.