http://www.ehow.com/how_4735491_write-professional-business-letter.html

http://owl.english.purdue.edu/owl/resource/653/01/

http://www.writeexpress.com/businessletters.html

http://www.writersreliefblog.com/post/Business-Letter-Format-How-To-Write-A-Professional-Business-Letter.aspx

http://www.ehow.com/how_4511758_write-thank-letter.html

http://www.rodmancpa.com/professional-business-letters.htm

http://cengagesites.com/academic/assets/sites/4004/1111063915_Writing%20Professional%20Letters.pdf

http://www.essortment.com/all/howtowriteab_rfby.htm

http://owl.english.purdue.edu/owl/resource/681/01

http://business.lovetoknow.com/wiki/Professional_Letter_Samples

http://www.essortment.com/career/writebusinessp_tuez.htm