Sharma, S.R.
Orient Longmans Ltd, 1951
Buku Teks
Brace, Richard M., author
Holt, Rinehart and Winston, 1961
Buku Referensi
Holtom, Daniel Clarence, 1884-1962, author
Paragon, 1963
Buku Teks
Smith, Leslie, author
Macmillan, 1989
Buku Teks
Snyder, Louis L., author
D. van Nastrand Company, Inc., 1967
Buku Teks