Silvio Ghilardi Roberto Sebastiani Frontiers of Combining Systems, 7th International Symposium, FroCoS 2009, Trento, Italy, September 16-18, 2009. Proceedings 5749 2009 http://dx.doi.org/10.1007/978-3-642-04222-5 978-3-642-04221-8 FroCoS Lecture Notes in Computer Science Springer db/conf/frocos/frocos2009.html