1. T. R. Gheewala M. J. Colwell H. H. Yang D. G. Breid "Dual-height Cell with Variable Width Power Rail Architecture " in US Patent US6838713 2005 T. R. Gheewala M. J. Colwell H. H. Yang D. G. Breid "Dual-height Cell with Variable Width Power Rail Architecture " in US Patent US6838713 2005