edited by Mildred F. Schmertz
McGraw-Hill, 1972
Buku Referensi
edited by Mildred F. Schamertz
McGraw-Hill, 1972
Buku Teks
Ojeda, Oscar Riera, author
Rockport Publishers, 1997
Buku Referensi
Wright, Paul H.
Buku Teks
Wright, Paul H., author
John Wiley & Sons, 1989
Buku Teks