Giuseppe Castagna Mariangiola Dezani-Ciancaglini Elena Giachino Luca Padovani Foundations of session types. 219-230 2009 PPDP http://doi.acm.org/10.1145/1599410.1599437 conf/ppdp/2009 db/conf/ppdp/ppdp2009.html#CastagnaDGP09