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4R. David Lankes. Building the Virtual Reference Desk.http://www.vrd. org/whitepaper, shml.
5Joann M. Wasik. Building and Maintaining Digital Reference Services. http://www, ericit.org/digests/.
624/7 Reference Project.(http:www.247ref.org/)
7Real-Time Reference for Undergraduates in Science.Mathematics,and Engineering.(http://www.library.cmu.edu/Libraries/24x7.pdf).
8Ask A Lbrarian.(http://www.earl.org.uk/ask/)
9Collaborative Digital Reference Service.(http://lcweb.loc.gov/rr/digiref/)
10D. 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)
