Brown, John Mason, author
Harper & Row, 1965
Buku Teks
Khatak, S.K.
Lahore Ashraf 1944
Buku Teks
Russel, Francis
McGraw-Hill Book, , 1958
Buku Teks
Beatty, Charles
Harper & Brothers Publishers, 1956
Buku Teks
McCullough, Helen Craig, author
Princeton University Press, 1980
Buku Teks