Seligman, Eustace
New York University Press, 1956.
Buku Teks
Rosinger, Lawrence K.
Macmillan, 1950
Buku Teks
Galsworthy, John
William, 1933
Buku Teks
Arora, Satish K.
Holt, Rinchart and Winston , 1969
Buku Teks
Farnsworth, E. Allan
Oceana Publications,Inc, 1963
Buku Teks