Alternative Traffic Sources

"I had close to 33,000 clicks in May and around 600,000 AdSense impressions. My average pay per click comes roughly less than 30 cents or so. Unique visitors 187,000 according to my awstats. Roughly 80% of my traffic referrals comes from 7 major universities (4 American, 2 Canadian, 1 Swedish) who included link to my site in various journal/article references and abstracts on their pages. I assume that most of my traffic is comprised of students." Mohammad_R