Danny Z. Chen Xiaobo Sharon Hu Shuang (Sean) Luan Shahid A. Naqvi Chao Wang Cedric X. Yu Generalized Geometric Approaches for Leaf Sequencing Problems in Radiation Therapy. 1176-1186 2005 conf/isaac/2005 ISAAC http://dx.doi.org/10.1007/11602613_116 db/conf/isaac/isaac2005.html#ChenHLNWY05