@INPROCEEDINGS{Melikov95,
    author = "Melikov, A. Z. and Ponomarenko, L. A.",
    title = "On the approach to optimal control 
      of queuing systems with multiple classes of customers",
    booktitle = "Proc.\ International Conf.\ on Syst.\ Sci.\ XII.",
    address   = "Wroclaw (Poland)",
    year = 1995,
    pages = "507-515"
}
