Nixon R. Rosemary, Gude K. Kathy, & Duckworth M. Michael. (2003). Matrix. Pre-Intermediate: Workbook (4-th ed.). New York, Oxford University Press, 2003.

Nixon R. Rosemary, Gude K. Kathy, and Duckworth M. Michael. Matrix. Pre-Intermediate: Workbook. 4-th ed. New York, Oxford University Press, 2003, 2003.

Nixon R. Rosemary, et al. Matrix. Pre-Intermediate: Workbook. 4-th ed. New York, Oxford University Press, 2003, 2003.