Brown, L. Neville (Lionel Neville), author
Sweet and Maxwell, 1994
Buku Teks
Hallenbeck, Wilbur C., author
Harper & Brothers , 1951
Buku Teks
University Press, 1949
Buku Teks
Nelson, Gary M., author
Barret-Koehler Publishers, Inc., 2000
Buku Teks
Buku Teks