Martín Abadi Luca Cardelli Benjamin C. Pierce Gordon D. Plotkin Dynamic Typing in a Statically-Typed Language. 213-227 1989 conf/popl/1989 POPL db/conf/popl/popl89.html#AbadiCPP89 http://doi.acm.org/10.1145/75277.75296 long version: TOPLAS 13 (2): 237-268 (1991)