Gaya APA

SCHOENBERG, I, E. (2001). Focus on grammar : an introductory course for reference and practice / Irene E. Schoenberg . S.L.: Longman.

Gaya MLA

SCHOENBERG, Irene, E.. "Focus on grammar : an introductory course for reference and practice / Irene E. Schoenberg". S.L.: Longman, 2001. Text.