Andrea Asperti Ferruccio Guidi Claudio Sacerdoti Coen Enrico Tassi Stefano Zacchiroli A Content Based Mathematical Search Engine: Whelp. 17-32 2004 conf/types/2004 TYPES http://dx.doi.org/10.1007/11617990_2 db/conf/types/types2004.html#AspertiGCTZ04