Ran Raz Amir Yehudayoff Lower Bounds and Separations for Constant Depth Multilinear Circuits. 128-139 2008 IEEE Conference on Computational Complexity http://doi.ieeecomputersociety.org/10.1109/CCC.2008.8 conf/coco/2008 db/conf/coco/coco2008.html#RazY08