@inproceedings{113468,
 author = {Tim Freeman and Frank Pfenning},
 title = {Refinement types for ML},
 booktitle = {Proceedings of the ACM SIGPLAN 1991 conference on Programming language design and implementation},
 year = {1991},
 isbn = {0-89791-428-7},
 pages = {268--277},
 location = {Toronto, Ontario, Canada},
 doi = {http://doi.acm.org/10.1145/113445.113468},
 publisher = {ACM Press},
 }