Patrice A. Spurck, Mary L.Mobr, Martha Stoner. (1995) The Impact of a Wireless Telecommunication System on Time Efficiency. Journal of Nursing Administration, 25, No.6, 21–26.
 Ping Wang et al. (2006) IEEE 802.11e enhancement for voice service. IEEE wireless communication, 13, Issue 1, 30–35.
 Yi Qian, Rose Qingyang Hu, Hsaio-Hwa Chen. (2006) A call ad-mission control framework for voice over WLANs. IEEE wireless communication, 13, Issue 1, 44–50.
 Chung-Lei Huang, Yin-Jiun Tseng, Woei C.Chu. (2005) The Design of a Computerised Drug Delivery Cart for Nursing Usage. APCMBE, PA-2-21.
 Daniel Collins. (2003) Carrier Grade Voice Over IP, 2nd ed. McGraw-Hill, 162-234.
 M. Handley, et al. (2002) SIP: Session Initiation Protocol. Internet Engineering Task Force, RFC3261.