Hawgood, John A.
Macmillan and co., limited, 1939
Buku Teks
New York University Press, 1951
Buku Teks
Moore, Russell F., author
Littlefield, Adams, 1957
Buku Teks
N. M. Tripathi Private, 1968
Buku Teks
Schwartz, Bernard, author
New York University Press, 1956
Buku Teks