The following publications are possibly variants of this publication:
- ACT ONE - An Algebraic Specification Language with two Levels of SemanticsHartmut Ehrig, Werner Fey, Horst Hansen. adt 1983:
- Pragmatics, concepts, syntax, semantics and correctness notions ACT TWO: an algebraic module specification and interconnection languageWerner Fey. PhD thesis, Technical University of Berlin, Germany, 1988. [doi]
- The Module Specification Language ACT TWOWerner Fey. adt 1986:
- Algebraic Theory of Module Specification with ConstraintsHartmut Ehrig, Werner Fey, Francesco Parisi-Presicce, Edward K. Blum. mfcs 1986: 59-77
- Categories for the Development of Algebraic Module SpecificationsHartmut Ehrig, Werner Fey, Horst Hansen, Michael Löwe, Francesco Parisi-Presicce. category 1989: 157-184
- Algebraic Specification of Modules and Configuration FamiliesHartmut Ehrig, Werner Fey, Horst Hansen, Michael Löwe, Dean Jacobs, Anno Langen, Francesco Parisi-Presicce. eik, 25(5/6):205-232, 1989.
- On the Relationship Between Algebraic Module Specifications and Program ModulesMichael Löwe, Hartmut Ehrig, Werner Fey, Dean Jacobs. tapsoft 1991: 83-98