Friendly, Fred W.
Random House, 1984
Buku Teks
Welch, Joseph N., author
Houghton Miffiln, 1956
Buku Teks
by William B. Lockhart ... [and others]
West Publishing Company, 1975
Buku Teks
Barker, Lucius J., author
Prentice-Hall, 1978
Buku Teks
Friendly, Fred W.
Random House, 1984
Buku Teks