Gaya APA

Schoenberg, I, E., Maurer, J. (2006). Focus on GRAMMAR 1 (2). United States of America: Pearson Longman.

Gaya MLA

Schoenberg, Irene, E.., Maurer, Jay. "Focus on GRAMMAR 1". 2 United States of America: Pearson Longman, 2006. Text.