Joost van Beusekom Faisal Shafait Thomas M. Breuel Document Signature Using Intrinsic Features for Counterfeit Detection. 47-57 2008 IWCF http://dx.doi.org/10.1007/978-3-540-85303-9_5 conf/iwcf/2008 db/conf/iwcf/iwcf2008.html#BeusekomSB08