Ward, Aidan
John Wiley & Sons Ltd, 2003
Buku Teks
Covey, Stephen M.R.
Free Press, 2012
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Obrien, Rita Cruise
John Wiley & Sons, 2001
Buku Teks
Covey, Stephen M.R.
Free Press, 2008
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Arief Hendarto
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2014
UI - Skripsi (Membership)