Bibliografi: hlm 187-199
No Inv.: 131805/S/Perp/12/1c
No Inv.: 124546-124550/P/Perp/10/5c
No Inv.: 114566/S/Perp/08/1c
Bibliografi : hlm. 253-254
Bibliografi : hlm. 235-236
Judul asli : "The Powerful purpose of Introverts"
Bibliografi : hlm. 147-153
Bibliografi : hlm. 169-174