Useful English Reference Works

Monolingual Online Dictionaries

Macmillan English Dictionary. A very good free option for advanced learners, with featured words and clickable pronunciation guides. You can set the default option for British or American English here.

Longman Dictionary of Contemporary English Online. With useful corpus examples for each word.

The Cambridge Dictionary website links to a number of useful dictionaries and reference guides. You can also set English-German and German-English options.

Oxford Advanced Learner's Dictionary. You can toggle between English and American English on the main search bar.

Collins English Dictionary. A good all-rounder. There is also a thesaurus function and an English-German option. And a Scrabble list!

Vocabulary.com. Definitions with up-to-date real world examples from sources such as the New York Times.

Merriam-Webster. The standard American English work. It also has a thesaurus function.

Oxford English Dictionary. Known as "the definitive record of the English language". It contains etymology and history as well as definitions. The university has a subscription which you can access while logged into the campus network.

Ozdic.com. A useful collocations dictionary and reference work, with a straightforward interface.

Urban Dictionary. A crowd-sourced reference for slang, colloquial expressions and very modern English.

Other Useful Resources

Academic Phrasebank. This database, created by John Morley at the University of Manchester, has an extensive collection of useful phrases for academic speaking and writing. There is also a version that can be purchased and downloaded for off-line use.

English Grammar Today is another option on the extensive Cambridge Dictionary website. It functions via a search box as well as an A-Z browsing function - useful if you don't know the exact term for what you want! British English only.

There is also a useful Grammar Guide from Oxford Dictionaries - the interface is slightly less crowded than the Cambridge version. British English only.

SKELL - Sketch Engine (language corpora software) for language learning. The simplifed student interface has a lot of interesting options for exploring and describing authentic language use.

Grammar Reference and
Practice Recommendations - print

Grammar Guides

* Michael Swan. Practical English Usage. 3rd ed. Oxford: Oxford University Press, 2010.

This is an excellent reference grammar for students. It is also available as an e-book and as an app (Android/Apple/Windows).

* John Stevens. Handbuch des englischen Sprachgebrauchs: ein Ratgeber für Zweifelsfälle. 2rd ed. (rev.) Stuttgart: Klett, 2012.

A very useful collection of explanations.

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Grammar Practice Works - Advanced

* Martin Hewings. Advanced Grammar in Use with Answers: A Self-Study Reference and Practice Book for Advanced Learners of English. 3rd ed. (rev.). Cambridge: Cambridge University Press, 2013.

One of the classic collections of practice activities. (Note that it is at times extremely British!)

* Mark Foley and Diane Hall. Advanced learners' grammar: a self-study reference & practice book with answers. Harlow, Essex: Longman, 2011.

* George Yule. Oxford practice grammar advanced: with answers. Oxford: Oxford University Press, 2008 ed.

** Michael Swan and Catherine Walter. Oxford English Grammar Course: Advanced. Oxford: Oxford University Press, 2011. 

Draws on the material in Swan's reference grammar, as he is a co-author. Once of the best options for truly advanced learners.

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Grammar Practice Works - Intermediate

If you find yourself needing to brush up on the basics, the following works are recommended.

* Raymond Murphy. English grammar in use: a self-study reference and practice book for intermediate learners of English. 4th ed. Cambridge: Cambridge University Press, 2015. 

There is also a mobile app for all operating systems.

* Mark Lloyd and Jeremy Day. Active grammar: level 3. Cambridge: Cambridge University Press, 2011.

(One of the few upper-intermediate practice works directly targeting the teen/young adult market.)

* Malcolm Mann and Steve Taylore-Knowles. Destination C1 & C2: Grammar & Vocabulary. Ismaning: Hueber (Macmillan), 2008.