Ronstadt, Robert
Natick Lord Publishing , 1988
Buku Teks
Firdaus Abdullah, author
Utusan Publications , 2013
Buku Teks
Hegar, Kathryn
Houghton Mifflin, 1985
Buku Teks
Paulson, Edward, author
Prenada Media, 2003
Buku Teks
Keith, Lyman A., author
McGraw-Hill, 1975
Buku Teks