Rilla Khaled Pippin Barr James Noble Ronald Fischer Robert Biddle Fine Tuning the Persuasion in Persuasive Games. 36-47 2007 conf/persuasive/2007 PERSUASIVE http://dx.doi.org/10.1007/978-3-540-77006-0_5 db/conf/persuasive/persuasive2007.html#KhaledBNFB07