@article{BGL91,
author = {R. Barbuti and R. Giacobazzi and G. Levi},
title = {A {G}eneral {F}ramework for {S}emantics-based 
         {B}ottom-up {A}bstract {I}nterpretation of {L}ogic {P}rograms},
year = {1993},
journal = "ACM Transactions on Programming Languages and Systems",
volume="15",
number= "1",
pages = {133-181}}