Vidiella, Alex Sanchez
Page one publishing pte ltd, 2011
Buku Referensi
Crosbie, Michael J.
Rockport Publishers, 1998
Buku Teks
Wagner, Walter F.
New York: McGraw-Hill, 1978
Buku Teks
Tobias Waltjen, Walter Pokorny, Thomas Zelger, Karl Tonghele
Springer, 2007
Buku Referensi
Reyes, Elizabeth V.
Periplus, 2000
Buku Teks