Liu, Jia
The Evaluation of worldwide digital reference services in libraries
Chandos Publishing, 2007
 Buku Teks SO
Guidelines for reference and information services in public libraries / Library Association Information Services Group
Library Association Publishing, 1999
 Buku Referensi
Innovation in libraries and information services
edited by David Baker and Wendy Evans
Emerald, 2017
 eBooks
Journal of youth services in libraries
American Library Association, 2018
 Majalah, Jurnal, Buletin
Conflicts in reference services
edited by Bill Katz
Haworth Press, 1985
 Buku Teks SO