Steensgaard-Madsen, J. " Statement-Oriented Approach to Data Abstraction" pp1-10

(1981) TOPLAS 3(1) January 1981  

Languages mentioned CLU {1974} CLUster programming language - abstractions and iterators Concurrent Pascal {1972} Dialect of Pascal which supports monitors Mesa {1977} XPARC Algol dialect Modula {1977} Concurrent modular language after Pascal SIMULA 67 {1967} Object-oriented simulation language