Sreekrishna Madhwapathy Naveed A. Sherwani Siddharth Bhingarde Anand Panyam A Unified Approach to Multilayer Over-the-Cell Routing. 182-187 1994 DAC http://doi.acm.org/10.1145/196244.196332 db/conf/dac/dac94.html#MadhwapathySBP94