Gaya APA

Purba, O, D., Hartiwi, . (2019). Happy Person (Daily Routines to Be a Happy Person) (cet. 1). Yogyakarta: Laksana.

Gaya MLA

Purba, Olivia, Dianina., Hartiwi, . "Happy Person (Daily Routines to Be a Happy Person)". cet. 1 Yogyakarta: Laksana, 2019. Text.