[ The grammar of vim ]
http://stackoverflow.com/questions/1218390/what-is-your-most-productive-shortcut-with-vim/1220118#1220118

https://gist.github.com/gmccreight/7519289 via http://nerds.weddingpartyapp.com/tech/2013/11/17/mastering-vim-in-vim/

[ A tutorial ]
http://www.danielmiessler.com/study/vim/