Grammar and Usage
Allsop, J. and L. Woods. 1990. Making Sense of Idioms. London: Cassell.
Eastwood, J. 1999. Oxford Practice Grammar. Oxford: Oxford U. P.
Ferguson, R. 1992. English Synonyms & Antonyms. London: Penguin.
Hayakawa, S. I. y E. Ehrlich. 1996. Guide to Synonyms and Related Words. London: Penguin.
Murphy, R. and R. Altman. 1989. Grammar in Use. Reference and Practice for Intermediate Students of English. Cambridge: Cambridge U. P.
Thomson, A. J. and A. V. Martinet. 1986. A Practical English Grammar. Oxford: Oxford U. P.
Dictionaries
English Thesaurus. 1995. New Lanark: Brockhampton Press.
Gondar, M. T. (Ed.). 2002. Cambridge Klett Compact. Español/Inglés, English/Spanish. Cambridge: Cambridge U. P.
Jones, D., P. Roach (Ed.), J. Hartman (Ed.) and J. Setter (Ed.). 2003. English Pronouncing Dictionary. Cambridge: Cambridge U. P.
Leech, G., V. Cook, W. Crombie, Y. Ikegami, P. Meara, R. O’Neill, P. Scholfied and K. Togo. 1993. Longman Language Activator: The World’s First Production Dictionary. Essex: Longman Group UK Limited.
Pearsall, J. (Ed.). 2002. The Concise Oxford English Dictionary. Oxford: Oxford U. P.