Denis Béchet Alexander Ja. Dikovsky Annie Foret Emmanuelle Garel Optional and Iterated Types for Pregroup Grammars. 88-100 2008 LATA http://dx.doi.org/10.1007/978-3-540-88282-4_10 conf/lata/2008 db/conf/lata/lata2008.html#BechetDFG08