APA (7th ed.) Citation

Christianti, D., Robertha, A., & Anasthasia, r. (2016). Basic speaking of English. Grasindo.

Chicago Style (17th ed.) Citation

Christianti, Diana, Astrid Robertha, and ruth Anasthasia. Basic Speaking of English. Grasindo, 2016.

MLA (8th ed.) Citation

Christianti, Diana, et al. Basic Speaking of English. Grasindo, 2016.