Pigors, Paul, author
McGraw-Hill, 1956
Buku Teks
Pigors, Paul, author
McGraw-Hill , 1961
Buku Teks
Pigors, Paul, author
McGraw-Hill, 1969
Buku Teks
Pigors, Paul, author
McGraw-Hill, 1981
Buku Teks
Sylvia, Ronald D.
Harcourt College Publisher, 2002
Buku Teks