The Cambridge guide to English usage
In dictionary format for easy reference this proves to be a useful companion to writing and for improving general use of English for both native and non-native speakers of English.
There are over 4000 extensive entries covering some of the most problematic areas of word choice, phraseology, grammar points and spelling (with information on American, Canadian and Australian variations).
This is a comprehensive guide to spoken and written English usage
EN DICO 29 (3 copies) Open access