@article {DBLP:journals/toplas/BrogiMPT94, title = {Modular Logic Programming}, journal = {ACM Trans. Program. Lang. Syst.}, volume = {16}, number = {4}, year = {1994}, pages = {1361-1398}, author = {Antonio Brogi and Paolo Mancarella and Dino Pedreschi and Franco Turini} }