Gaya APA
Ekeren, G, V. (2000).
12 simple secrets of happiness : finding joy in everyday relationships .
United States Of America:
Prentice Hall.
Gaya MLA
Ekeren, Glee, Van.
"12 simple secrets of happiness : finding joy in everyday relationships".
United States Of America:
Prentice Hall,
2000.
Buku.