Alexander, L.G. (1992). Longman English Grammar Practice for intermediate students. Essex:
Longman Group UK Limited.
Azar, Betty Schrampfer. (1993). Understanding and Using English Grammar. Chartbook: a
Reference Grammar. Second Edition. Englewood Cliffs, New Jersey: Prentice Hall, Inc.
Spankle, G.M. (1987). The Grammar You Need. London and Basingstoke: Macmillan Publishers Ltd.
Swan, Michael. (1981). Practical English Usage. Oxford: Oxford University Press.
____________. (1985). Basic English Usage. Oxford: Oxford University Press.
Vince, Michael and Emmerson, Paul. (2003). English Grammar and Vocabulary: Intermediate
