Roberto M. Amadio, Luca Cardelli. Subtyping Recursive Types. ACM Transactions on Programming Languages and Systems, 15(4):575-631, 1993. [doi]
@article{AmadioC93,
title = {Subtyping Recursive Types},
author = {Roberto M. Amadio and Luca Cardelli},
year = {1993},
doi = {10.1145/155183.155231},
url = {http://doi.acm.org/10.1145/155183.155231},
tags = {subtyping},
researchr = {https://researchr.org/publication/AmadioC93},
cites = {0},
citedby = {0},
journal = {ACM Transactions on Programming Languages and Systems},
volume = {15},
number = {4},
pages = {575-631},
}