Minmin Chen Yixin Chen Michael R. Brent Aaron E. Tenney Gradient-Based Feature Selection for Conditional Random Fields and its Applications in Computational Genetics. 750-757 2009 ICTAI http://doi.ieeecomputersociety.org/10.1109/ICTAI.2009.82 conf/ictai/2009 db/conf/ictai/ictai2009.html#ChenCBT09