Ewald, Helen Rothschild, author
Prentice-Hall International, 1997
Buku Teks
Tubbs, Stewart L., author
Remaja Rosdakarya, 1996
Buku Teks
Tubbs, Stewart L., author
Remaja Rosdakarya, 1996
Buku Teks
Andersen, Kenneth E.
Cummings Publishing, 1972
Buku Teks
Dodd, Carley H.
McGraw-Hill, 1998
Buku Teks