Useful links
Grammar & Punctuation Tips (Jill Cienki, Stockton College)†
How to Write Consistently Boring Scientific Literature (Kaj Sand-Jensen, Oikos)
Manifesto for the Simple Scribe (Tim Radford, Guardian)
Write Stuff (Henry Gee, Nature)
Writer's Handbook (University of Wisconsin-Madison)
Writing Center Handouts (Harvard University)
Writing Center Handouts (University of North Carolina, Chapel Hill)
† Grateful thanks to Betsy Tackett for the links
Common Errors in English (Paul Brian, Washington State University)
Dr. Grammar (University of Northern Iowa)
Grammar Girl (Mignon Fogarty)
Guide to Grammar & Writing (Capital Community College Foundation)
Learn English (British Council)
Modern English Grammar (Daniel Kies, College of DuPage)
Skillswise (BBC)
Longman Dictionary of Contemporary English
Oxford Advanced Learner's Dictionary
Oxford English Dictionary (via NTU Library Website > Databases > 'O')