http://technmarketing.com/2011/08/twitter-to-follow-back-or-not-to-follow-back-how-to-decide/

http://www.mediabistro.com/alltwitter/how-to-twitter-infographic_b12491

http://technmarketing.com/2009/07/9-advanced-twitter-tips/

http://socialfresh.com/27-twitter-laws-to-follow/

http://mashable.com/2011/08/11/manchester-police-twitter/

http://technmarketing.com/2009/04/ten-things-you-must-know-before-using-twitter/

http://www.mediabistro.com/alltwitter/to-follow-or-not-to-follow-the-simple-twitter-tool-that-helps-you-decide_b12476