Burden, Ernest E., 1934-, author
McGraw-Hill, 2012
Buku Teks
Ching, Francis D.K., 1943-, author
John Wiley & Sons, 1997
Buku Teks
Commerma, Broto i
Page One, 2007
Buku Teks
edited by Maggie Toy
Academy Group, 1996
Buku Teks
Salvadori, Mario, author
Prentice-Hall, 1963
Buku Teks