Mariangiola Dezani-Ciancaglini Ugo de'Liguoro Adolfo Piperno Filter Models for a Parallel and Non Deterministic Lambda-Calculus. 403-412 1993 conf/mfcs/1993 MFCS db/conf/mfcs/mfcs93.html#Dezani-CiancaglinidP93 http://dx.doi.org/10.1007/3-540-57182-5_32