Philippe Pasquier Ramon Hollands Frank Dignum Iyad Rahwan Liz Sonenberg Exploiting Hierarchical Goals in Bilateral Automated Negotiation: Empirical Study. 46-61 2007 AMEC/TADA http://dx.doi.org/10.1007/978-3-540-88713-3_4 conf/atal/2007amec db/conf/atal/amec2007.html#PasquierHDRS07