Hiro Ito Hiroshi Nagamochi Comparing Hypergraphs by Areas of Hyperedges Drawn on a Convex Polygon. 176-181 http://dx.doi.org/10.1007/978-3-540-44400-8_18 2002 conf/jcdcg/2002 JCDCG db/conf/jcdcg/jcdcg2002.html#ItoN02