6ISO 2789:2006 Information and documentation International library statistics. Geneva, Switzerland: International organization for Standardization. Retrieved http://www.iso.org/iso/iso_catalogue/catalogue_tc/ catalogue_detail.htm?csnumber=39181,2008-07-25.
7ISO. ISO 11620 Information and documentation - Library performance indicators, http://www.iso.org/iso/ iso_catalogue/ catalogue_ics/ catalogue_detail_ics.htm? csnumber=37853,2008-7-25.
8Sumsion J. ISO 2789: what's new in and around the revision? Performance Measurement and Metrics, 2003,4 (3):103-112.