Lingling Fan Shuguang Wang Hongfa Wang Tiande Guo Singular Points Detection Based on Zero-Pole Model in Fingerprint Images. 929-940 2008 30 IEEE Trans. Pattern Anal. Mach. Intell. 6 http://doi.ieeecomputersociety.org/10.1109/TPAMI.2008.31 db/journals/pami/pami30.html#FanWWG08