Gaya APA

Schoenberg, I, E., Maurer, J. (2002). Focus on grammar: an introductory course for reference and practice . New York: Longman.

Gaya MLA

Schoenberg, Irene, E.., Maurer, Jay. "Focus on grammar: an introductory course for reference and practice". New York: Longman, 2002. Text.