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How to write proper :)
The King's EnglishThe King's English by Henry W. Fowler
Buy used from: £4.50
Full of excellent, witty advice on correct English usage. This seems to be very difficult to obtain, often going out of print. Check out ISBN 0198813309 as well.
Eats shoots and leaves: The Zero Tolerance Approach to PunctuationEats shoots and leaves: The Zero Tolerance Approach to Punctuation by Lynne Truss
Buy new: £6.99 / Used from: £0.23
The Oxford Style ManualThe Oxford Style Manual by Robert Ritter
Buy new: £16.25 / Used from: £15.79
The Penguin Guide to Punctuation (Penguin Reference Books)The Penguin Guide to Punctuation (Penguin Reference Books) by R.L. Trask
Buy new: £3.06 / Used from: £2.73
The Penguin Dictionary of English Grammar (Penguin Reference Books)The Penguin Dictionary of English Grammar (Penguin Reference Books) by R.L. Trask
Buy new: £2.87 / Used from: £3.00
Line by Line: How to Edit Your Own WritingLine by Line: How to Edit Your Own Writing
Buy new: £4.09 / Used from: £4.68
You Have a Point ThereYou Have a Point There by Eric Partridge
Buy new: £18.99 / Used from: £1.59
The Complete Plain WordsThe Complete Plain Words by Sir Ernest Gowers
Buy new: £6.99 / Used from: £1.28
Usage and Abusage: A Guide to Good English (Penguin Reference Books)Usage and Abusage: A Guide to Good English (Penguin Reference Books) by Eric Partridge
Buy new: £7.69 / Used from: £5.00
Fowler's Modern English Usage (Oxford Language Classics)Fowler's Modern English Usage (Oxford Language Classics) by H.W. Fowler
Buy used from: £14.99
Debrett's Correct Form (Debretts)Debrett's Correct Form (Debretts) by Patrick Montague-Smith
Buy used from: £6.93
Concise Oxford English DictionaryConcise Oxford English Dictionary by Oxford Dictionaries
Buy new: £17.50 / Used from: £7.47
Oxford Paperback ThesaurusOxford Paperback Thesaurus by Maurice Waite
Buy used from: £0.01
Oxford A-Z of Grammar and PunctuationOxford A-Z of Grammar and Punctuation by John Seely
Buy used from: £35.64
New Oxford Dictionary for Writers and Editors: The Essential A-Z Guide to the Written Word (Reference)New Oxford Dictionary for Writers and Editors: The Essential A-Z Guide to the Written Word (Reference)
Buy new: £7.79 / Used from: £7.03
New Hart's Rules: The Handbook of Style for Writers and Editors (Reference)New Hart's Rules: The Handbook of Style for Writers and Editors (Reference)
Buy new: £8.44 / Used from: £5.50
Rediscover GrammarRediscover Grammar by David Crystal
Buy new: £13.59 / Used from: £14.00
Making Sense of GrammarMaking Sense of Grammar by David Crystal
Buy new: £16.14 / Used from: £18.50