Schuller, Robert H.
Keuletan kunci keberhasilan : masa yang sulit tidak pernah berakhir, tetapi orang yang ulet akan berhasil mengatasinya
Gunung Mulia, 1986
 Buku Teks SO
Tambunan, Emil H.
Kepribadian Seutuhnya : terobosan mencapai hidup berdaya guna dan sukses
Indonesia Publishing House, 2007
 Buku Teks SO
Tracy, Brian
Change your thinking change your life : how to unlock your full potential for success and achievement
John Wiley & Sons, 2003
 Buku Teks
Bryan Lo`s
Wealth life : the easy lifestyle to achieve happiness, wealth and financial freedom
Awesome Books Publishing SDN BHN, 2002
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Tracy, Brian
Focal point: a proven system to simplify your life, double your productivity, and achieve all your goals
American Management Association, 2002
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