1. The Impact Factor (IF) of a journal in 2003 is defined by the Institute for Scientific Information (ISI) as: (the number of citations made in all journals published in 2003 to articles published in the journal in 2002 and 2001) divided by (the number of articles published in the journal in 2002 and 2001). Full details are available from the ISI, Philadelphia at http://www.isinet.com.