Gaya APA

Betty, A, S., A., H, S. (2011). Foundamentals Of English Grammar, Fourth Edition (KE-4). USA: Pearson Longman.

Gaya MLA

Betty, Azar, S.., A., Hagen, Stacy. "Foundamentals Of English Grammar, Fourth Edition". KE-4 USA: Pearson Longman, 2011. PBI.