Gaya APA

Langdon, R, M., Norris, W, B. (1961). American Foreign Policy (4). New Jersey: Littlefield, Adams & Co..

Gaya MLA

Langdon, Robert, M.., Norris, Walter, B.. "American Foreign Policy". 4 New Jersey: Littlefield, Adams & Co., 1961. Koleksi Elektronik.