Sparrow, Giles, 1970-
Quercus, 2014
Buku Referensi
Spadaccini, Michael
Ep Entrepreneuir Press, 2011
Buku Teks
Altman, Nathaniel
Healing Arts Press, 2000
Buku Teks SO
Biech, Elaine
ASTD press, 2009
Buku Teks
Sanders, Jack, 1944-
Ragged Mountain Press/McGraw-Hill, 2000
Buku Referensi