Ganesh Venkataraman Jiang Hu Frank Liu Integrated Placement and Skew Optimization for Rotary Clocking. 149-158 2007 15 IEEE Trans. VLSI Syst. 2 http://dx.doi.org/10.1109/TVLSI.2007.893577 db/journals/tvlsi/tvlsi15.html#VenkataramanHL07