Masayuki Terai Kazuo Nakajima Kazuhiro Takahashi Koji Sato A new approach to over-the-cell channel routing with three layers. 187-200 1994 13 IEEE Trans. on CAD of Integrated Circuits and Systems 2 http://doi.ieeecomputersociety.org/10.1109/43.259942 db/journals/tcad/tcad13.html#TeraiNTS94