Aukerman, Robert C.
John Wiley & Sons, 1981
Buku Teks
Blair, Walter, author
Scott, Foresman and Company, 1948
Buku Teks
Steven, Laurence, author
Prentice-Hall, 1999
Buku Teks
Oceana`s Docket Books, 1964
Buku Teks
Buckley, Lillian A., author
Citation Press, 1975
Buku Teks