From: <http://in-cites.com/top/2007/index.html&gt;

For each of the 22 fields below from the six bimonthly periods in 2007, the top 10 most-cited researchers are listed with ≥5 papers published and cited during specific bimonthly updates of Essential Science Indicators. (That is, 10-year plus each successive 2-month addition of publication and citation figures, through the most recently available update.) The rankings, based on overall citations, may change slightly from one bimonthly update to the next, as new papers and new citations are added to each researcher’s total.