Gaya APA
Duckworth, A. (1988).
GRIT : Why Passion and Resiliense are the Secrets to Success .
Surakarta:
Putra Jaya Surabaya.
Gaya MLA
Duckworth, Angela.
"GRIT : Why Passion and Resiliense are the Secrets to Success".
Surakarta:
Putra Jaya Surabaya,
1988.
Text.