Eskilson, Stephen
Laurence King , 2012
Buku Teks SO
Stevenson, George A.
McGraw-Hill, 1979
Buku Referensi
Daniels, Lawrence J., 1942-
[American Management Association;, ], 2013
eBooks
Bob Gordon, consultant editor; Maggie Gordon, consultant editor
Watson-Guptill Publications, 2002
Buku Teks SO
Norris, Christopher
Academy Editions, 1988
Buku Teks SO