Harrington, R.B., author
Dickenson, 1970
Buku Teks
Smith, Karl J., author
Brooks/Cole, 1994
Buku Teks
Fine, Nathan J., author
Rand McNally, 1965
Buku Teks
Fine, Nathan J., author
Rand McNally, 1965
Buku Teks
Smyrl, J.L., author
Hodder and Stoughton, 1978
Buku Teks