http://en.wikipedia.org/wiki/Business_letter

http://www.4hb.com/letters/

http://www.unc.edu/depts/wcweb/handouts/business.html

http://esl.about.com/cs/onthejobenglish/a/a_basbletter.htm

http://www.libraryonline.com/letters.asp?Cata_ID=33

http://jobsearchtech.about.com/od/letters/l/bl_block_p.htm

http://www.vanik.com/letters.htm

http://www.quazell.com/BusinessLetters/default.htm

http://writing.colostate.edu/guides/documents/business_writing/business_letter/

http://www.4hb.com/letters/index4.html