Le faccette, il web semantico e l’ornitorinco (Trovabile) – <http://www.trovabile.org/faccette_web_semantico_ornitorinco>

Platypus wiki: a semantic wiki wiki web / Stefano Emilio Campanini, Paolo Castagna, Roberto Tazzoli (SWAP: Semantic Web applications and perspectives : 1st Italian Semantic Web workshop : Ancona : 10th December 2004) – <http://semanticweb.deit.univpm.it/swap2004/cameraready/castagna.pdf>

Graph theory / Frank Harary – Addison-Wesley : Reading (Mass’) : 1969

Integrative level classification (ISKO Italia. Documenti) – <http://www.iskoi.org/ilc> : 2004-