Oronzo Altamura Floriana Esposito Francesca A. Lisi Donato Malerba Symbolic Learning Techniques in Paper Document Processing. 159-173 http://dx.doi.org/10.1007/3-540-48097-8_13 1999 conf/mldm/1999 MLDM db/conf/mldm/mldm99.html#AltamuraELM99