Johnson, Glen M., author
McGraw-Hill, 1999
Buku Teks
Johnson, Glenn M., author
McGraw-Hill, 1999
Buku Referensi
Whitehead, Randall, author
Rockport, 1998
Buku Teks
Szenasy, Susan S., author
Running Press, 1986
Buku Referensi
Whitehead, Randall, author
Rockport Publishers, 1993
Buku Referensi