Qian Huang King-Tim Ko Villy Bæk Iversen An Approximation Method for Multiservice Loss Performance in Hierarchical Networks. 901-912 2007 conf/teletraffic/2007 International Teletraffic Congress http://dx.doi.org/10.1007/978-3-540-72990-7_78 db/conf/teletraffic/itc2007.html#HuangKI07