3Real-Time Reference for Undergraduates in Science.Mathematics,and Engineering.(http://www.library.cmu.edu/Libraries/24x7.pdf).
4Ask A Lbrarian.(http://www.earl.org.uk/ask/)
5Collaborative Digital Reference Service.(http://lcweb.loc.gov/rr/digiref/)
6D. N. Kresh, Offering High Quality Reference Service on the Web. D-Lib Magazine6(6) ,June 2000. (http://www.dlib.org/dlib/june 00/kresh/06kresh. html)
7Virtual Reference Desk. (http://www.vrd.org)
8Virtnal Reference Desk:Building a Network of Expertise for America's Schools.(http://www.vrd.org/Workshop/WhitePaper.PDF)
