Muhammad T. Alam and  Zheng Da Wu,   Asymptotic Analysis of Instant Messaging Service with Relay Nodes .   journal   = {International Journal of Electronics and Communication Engineering}, [online]. World Academy of Science, Engineering and Technology.
    February 2007, vol. 2(2). 228 - 236
    [viewed 27 April 2024]. Available from: https://publications.waset.org/pdf/1624.