a selection of general/multidisciplinary online dictionaries, encyclopedias, thesauri and other reference tools are available for english language learners.
additional titles are listed below:
encyclopedia of language and education by nancy h. hornberger
handbook of research in second language teaching and learning (vols 1-2) by eli hinkel (editor)
routledge dictionary of language and linguistics (electronic resource) by trans. and ed. by gregory trauth.
routledge encyclopedia of language teaching and learning [electronic resource] by byram, michael