Schiffman, Leon G.
Pearson, 2015
Buku Teks SO
Schiffman, Leon G.
Pearson Education, Inc., 2007
Buku Teks SO
Engel, James F.
Chicago Dryden Press, 1990
Buku Teks SO
Schiffman, Leon G.
Pearson Education International, 2004
Buku Teks SO
Peter, J. Paul
Erlangga , 1999
Buku Teks SO