1. F. Baskett, K.M. Chandy, R.R. Muntz and G.F. Palacois, Open, closed and mixed networks of queues with different classes of customers, J. ACM 22 (1975) 248?260.
2. H. Beilner, J. Mater and N. Weissenberg, Towards a performance modelling environment: News on HIT, in:Proc. 4th Int. Conf. on Modelling Techniques and Tools for Performance Evaluation, ed. R. Puijanger (Plenum, New York, 1988).
3. A. Bobbio and K.S. Trivedi, An aggregation technique for the transient analysis of stiff Markov chains, IEEETrans. Comp. 35 (1986) 803?814.
4. P. Buchholz,The Structured Analysis of Markovian Models (in German) (Informatik Fachberichte 282, Springer, Berlin, 1991).
5. Informatik Fachberichte 286;P. Buchholz,1991