Selby, N. (1987). Essential college english: A grammar and puntuation workbook (2ª ed.). Norwood Selby.
Cita Chicago (17th ed.)Selby, Norwood. Essential College English: A Grammar and Puntuation Workbook. 2ª ed. Norwood Selby, 1987.
Cita MLA (9th ed.)Selby, Norwood. Essential College English: A Grammar and Puntuation Workbook. 2ª ed. Norwood Selby, 1987.
Atenció: Aquestes cites poden no estar 100% correctes.