@article{BCGL93,
	author = {R. Barbuti and M. Codish and R. Giacobazzi and G. Levi},
	title = {Modelling {P}rolog {C}ontrol},
	journal = {Journal of Logic and Computation},
	volume = 3, 
	number = 6,
        pages = {579-603},
	year = {1993}}