Cita APA (7a ed.)

Eckstut, S. (1994). Focus on grammar: Workbook. A basic course for reference and practice. Addison-Wesley.

Cita Chicago Style (17a ed.)

Eckstut, Samuela. Focus on Grammar: Workbook. A Basic Course for Reference and Practice. Massachusetts: Addison-Wesley, 1994.

Cita MLA (9a ed.)

Eckstut, Samuela. Focus on Grammar: Workbook. A Basic Course for Reference and Practice. Addison-Wesley, 1994.