“…Table 5 Keywords co-occurrence matrix B been paid attention to by scholars in China, because user information needs, service quality expectations, facilitated outcomes, and added values of digital libraries are realized through service process. Thus in the digital library era, it is certain that the people interested in digital libraries studies must think deeply how to develop Library Service (LibSer) to promote the services in digital libraries, such as how to bring out Personalized Information Service (PISer) or Personalized Service (P-Ser), as users' needs are not only a complex and constantly evolving issue, but also are never met because of their individual, personal and changing nature (Han and Goulding 2003). Among all the services in digital libraries, reference (Ref) and information services (InfoSer) are major components, which are constantly developing as is the library itself.…”