Haas, William S.
Columbia University Press, 1946
Buku Teks
Johnson, Edgar, author
Simon and Schuster, 1945
Buku Teks
Palgrave, Francis Turner
Walter J. Black Inc, 1932
Buku Teks
Kelly, Miles, author
Miley Kelly Publishing, 2010
Buku Teks
Cawthorne, Nigel, 1961-, author
Hamlyn, 1997
Buku Teks