Bo Xu Zhenbao Zhang Jiazhen Wang Xiaoqin Liu Improved BSS Based Schemes for Active Steganalysis. 815-818 2007 SNPD (3) http://doi.ieeecomputersociety.org/10.1109/SNPD.2007.311 conf/snpd/2007 db/conf/snpd/snpd2007-3.html#XuZWL07