APA (7th ed.) Citation
Soars, J., Soars, L., & Devoy, J. (1998). New Headway English Course. Upper-Intermediate Workbook with key. Oxford University Press.
Chicago Style (17th ed.) Citation
Soars, John, Liz Soars, and Jo Devoy. New Headway English Course. Upper-Intermediate Workbook with Key. Oxford: Oxford University Press, 1998.
MLA (9th ed.) Citation
Soars, John, et al. New Headway English Course. Upper-Intermediate Workbook with Key. Oxford University Press, 1998.
Warning: These citations may not always be 100% accurate.