Imam Subekti
Fakultas Kedokteran Universitas Indonesia, 2016
UI - Makalah dan Kertas Kerja
Kuczmarski, Thomas D.
Prentice-Hall International, 1992
Buku Teks SO
Trott, Paul
Pearson Education , 2017
Buku Teks SO
Dundon, Elaine
American Management Association, 2002
eBooks
Levitt, Theodore
Pan Books, 1962
Buku Teks SO