Backhouse, Roland C., author
Prentice-Hall, 1979
Buku Teks
Appleby, Doris, author
McGraw-Hill, 1991
Buku Teks SO
Jhon Wiley & Sons , 1991
Buku Teks SO
Cherry, Edith
John Wiley & Sons, 1999
Buku Teks
Gorrell, Paul. author
Cambridge University Press, 2006
Buku Teks