Web2
ftp://snow.shinshu-u.ac.jp/pub/
ワードスミス
http://www.liv.ac.uk/~ms2928/
Word Frequencies in Written and Spoken English: based on the British National Corpus. -
Geoffrey Leech, Paul Rayson, Andrew Wilson
http://www.comp.lancs.ac.uk/ucrel/bncfreq/
書籍：O'Reilly Japan
http://www.oreilly.co.jp/