Eiffel-like Assertions and Private Methods in Smalltalk. - Manuela Carrillo-Castellon; Jesús García Molina; Ernesto Pimentel 001 (TOOLS (13), 1994)

Design by Contract in Smalltalk. - Manuela Carrillo-Castellon; Jesús García Molina; Ernesto Pimentel 001; Israel Repiso (J. Object Oriented Program., 1996)