Mohammad Hossain Heydari Ioannis G. Tollis Chunliang Xia Algorithms and bounds for layer assignment of MCM routing. 265-270 1994 2 IEEE Trans. VLSI Syst. 2 http://doi.ieeecomputersociety.org/10.1109/92.285755 db/journals/tvlsi/tvlsi2.html#HeydariTX94