http://writing2.richmond.edu/writing/wweb/brainst.html
http://writing2.richmond.edu/writing/wweb/cluster.html
http://www.unc.edu/depts/wcweb/handouts/brainstorming.html
http://www.dlsweb.rmit.edu.au/lsu/content/1_StudySkills/09mindmaps.html
http://www.sass.uottawa.ca/writing/kit/stage2-brainstorming.php