Gaya APA

Peterson, P, W. (1980). Changing Times, Changing Tenses: A Review Of The English Tense System (-). USA: International Commnication Agency.

Gaya MLA

Peterson, Patricia, Wilcox. "Changing Times, Changing Tenses: A Review Of The English Tense System". - USA: International Commnication Agency, 1980. Buku.