Usage

USAGE and word choice
University of Victoria (great campus!) usage guide
http://www.ltn.lv/~markir/writersguide/Pages/DictionUsageToc.html

Cohesion devices: logical connectors a.k.a. signposts a.k.a. connectives,
http://sana.aalto.fi/awe/cohesion/signposts/index.html
BTW: explore this site – it contains good things but the navigation doesn’t tell you much.

USAGE and style guides

Garner’s Modern English Usage introduced here

The Economist style guide for seven pounds is indispensable for GRIPS students.
The Economist magazine also has a free style guide; although it is simple, it is solid.
http://www.economist.com/styleguide/introduction

Grammar Girl web site and podcasts (despite the name, a serious contemporary usage resource)
http://grammar.quickanddirtytips.com/
MIT’s ComDor Editorial Style Guide
http://web.mit.edu/comdor/editguide/
Writing Technical Articles
http://www.cs.columbia.edu/~hgs/etc/writing-style.html
Technical Writing
http://www.rbs0.com/tw.htm
Strunk and White’s The Elements of Style online
http://www.bartleby.com/141/
The Coventry University Harvard Reference Style is here
Journalistic style:  the 4-box system
http://www.mcgillreport.org/largemouth.htm#anchor4
Google ngrams: a pretty cool tool:
https://books.google.com/ngrams

USAGE: Concordance
1. Fantastic! Three great concordance samplers which can access the biggest and most famous corpuses (including the British National Corpus) are:
http://www.lextutor.ca/conc/eng/
http://corpus.byu.edu/
British Academic Written English concordancer
https://the.sketchengine.co.uk/corpus/first_form?corpname=preloaded/bawe2;
British Academic Written English Corpus
http://www.coventry.ac.uk/research/research-directories/current-projects/2015/british-academic-written-english-corpus-bawe/

2. Make your own concordance! Laurence Antony at Waseda  University made Antconc, a free software for making your own concordance.
http://www.laurenceanthony.net/software.html

3. Google can be a simple concordancer too:
http://www.johntedesco.net/blog/2012/06/21/how-to-solve-impossible-problems-daniel-russells-awesome-google-search-techniques/