Frank Dignum, Rogier M. van Eijk, Roberto A. Flores: Agent Communication II, International Workshops on Agent Communication, AC 2005 and AC 2006, Utrecht, Netherlands, July 25, 2005 and Hakodate, Japan, May 9, 2006, Selected and Revised Papers. Lecture Notes in Computer Science 3859, Springer 2006, ISBN 978-3-540-68142-7