Scott, Walter Dill, author
McGraw-Hill, 1959
Buku Teks
Jackson, Susan E., author
South Westh Western College, 2000
Buku Teks
Storey, John, 1950-, author
Blackwell, 1992
Buku Teks
Sikula, Andrew F.
John Weley, 1984
Buku Teks
Schmitt, Neal W.
South-Western Publishing, 1991
Buku Teks