2Association of Research Libraries. E-Metrics:Measures for Electronic Resources [EB/OL]. [ 2010-05-03 ]. http :// www.arl.org/stats/initiatives/emetric s/index.shtml.
3Paula T. Kaufman. The Library as Strategic Invest- ment:Results of the Illinois Return on Investment Study [J]. Liber Quarterly, 2008,18 (3/4) :424-436.