Jisheng Liang Vikram Chalana Ihsin T. Phillips Robert M. Haralick A Methodology for Special Symbol Recognitions. 4011-4014 2000 ICPR http://csdl.computer.org/comp/proceedings/icpr/2000/0750/04/07504011abs.htm db/conf/icpr/icpr2000-4.html#LiangCPH00