1. Bar‐Ilan, J. (1999), “Search engine results over time – a case study on search engine stability”, Cybermetrics, Vol. 2/3. http://www.cindoc.csic.es/cybermetrics/articles/v2i1p1.html
2. Chu, H. and Rosenthal, M. (1996), “Search engines for the World Wide Web: a comparative study and evaluation methodology”, ASIS96, http://www.asis.org/annual‐96/Electronic‐Proceedings/chu.html
3. Ding, W. and Marchionini, G. (1996), “A comparative study of Web search service performance”, ASIS96, http://www.glue.umd.edu/∼weid/asis/fulltext.html
4. SEARCH ENGINES ON THE WORLD WIDE WEB AND INFORMATION RETRIEVAL FROM THE INTERNET: A REVIEW AND EVALUATION
5. Halperin M. and Cavanaugh, B.B. (1998), “Onsite loading vs. offsite access – Ovid options”, Database, Vol. 21, June/July, pp. 30‐34.