Keedy, Mervin J., author
Addison-Wesley , 1969
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
Munro, John E., author
Chapman & Hall, 1992
Buku Teks