edited by Rachel Hewes, Allison Hodges
Rockport, 2012
Buku Referensi
Levens, A.S., author
John Wiley & Sons, 1980
Buku Teks
Ciriello, Marco, author
McGraw-Hill, 2002
Buku Teks
Hewes ,Rachel, author
Rockport Publishers, 2010
Buku Referensi
Ambrose, James E., author
Wiley, 1992
Buku Teks