1. Abstraction and Specification in Program Development;Liskov,1986
2. Learning the language;Wegner;Byte,1989
3. Flowchart techniques for structured programming;Nassi;SIGPLAN Notices,1973
4. J.A. Goguen and J. Meseguer, Unifying functional, object-oriented and relational programming with logical semantics, In: [30].
5. Beyond programming languages;Winograd;CACM,1979