Copi, Irving M., author
Macmillan, 1961
Buku Teks
Copi, Irving M., author
Prentice-Hall, 1995
Buku Teks
Copi, Irving M., author
Prentice-Hall, 1979
Buku Teks
Dalen, Dirk van, author
Springer-Verlag, 1994
Buku Teks
Maier, David, author
The Benjamin Cumming Pub., 1988
Buku Teks