Embedding Multiset Constraints into a Lazy Functional Logic Language. - Puri Arenas-Sánchez; Francisco Javier López-Fraguas; Mario Rodrúguez-Arteljo (PLILP/ALP, 1998)

Functional Plus Logic Programming with Built-In and Symbolic Constraints. - Puri Arenas-Sánchez; Francisco Javier López-Fraguas; Mario Rodrúguez-Arteljo (PPDP, 1999)