1White, M. D. Diffusion of an Innovation: Digital Reference Service in Carnegie Foundation Master's (Comprehensive)Academic Institution Libraries. Journal of Academic Librarianship, 2001,27(3) :173-187.
4R. David Lankes. "Introduction : The Foundations of Digital Reference" in The New Library Series:Digital Reference in the New Millennium: Planning, Management, and Evaluation. Number 6,NewYork: Neal - Schuman. 2000.9.
5Goetsch, Loft, Electronic Reference Service. SPEC Kit 251. Washington,DC:Office of Leadership and Management Services, Association of Research Libraries, 1999.
7Trix Bakker. Virtual Reference Services:Connecting Users with Experts and Supporting the Developmentof. Skills. Liber Quarterly:the Journal of European Research Libraries,2002.12 (2/3): 124 - 137.[ Online ]. http://webdoc.gwdg.de/edoc/aw/liber/lq - 2 - 02/124 - 137. pdf.