Elliott, William Y.
Prentice-Hall, 1950
Buku Teks
Easton, Stewart C.
Holt, Rinehart and Winston, 1966
Buku Teks
edited by John Louis Beatty, Oliver A. Johnson
Prentice-Hall, 1966
Buku Teks
McDonald, Lee Cameron
Harcour Brace Jovanwich, 1968
Buku Teks
Sharma, R.P.
Sterling Publishers Private, 1984
Buku Teks