Great Northern Railway Company (U.S.). (1921). Zone of plenty: Minnesota, North Dakota, Montana, Washington, Oregon, Idaho. Great Northern Railway.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रGreat Northern Railway Company (U.S.). Zone of Plenty: Minnesota, North Dakota, Montana, Washington, Oregon, Idaho. [Saint Paul, Minn.]: Great Northern Railway, 1921.
एमएलए (8वां संस्करण) प्रशस्ति पत्रGreat Northern Railway Company (U.S.). Zone of Plenty: Minnesota, North Dakota, Montana, Washington, Oregon, Idaho. Great Northern Railway, 1921.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.