ACT ONE - An Algebraic Specification Language with two Levels of Semantics. - Hartmut Ehrig; Werner Fey; Horst Hansen (ADT, 1983)

Towards Abstract User Interfaces for Formal System Specifications. - Hartmut Ehrig; Werner Fey; Horst Hansen (ADT, 1984)

From Algebraic Specifications towards Algebraic Programs. - Horst Hansen (ADT, 1986)

Von algebraischen Spezifikationen zu algebraischen Programmen. - Horst Hansen (1986)

The ACT System: Experiences and Future Enhancements. - Horst Hansen (ADT, 1987)

Algebraic Theory of Modular Specification Development. - Werner Fey; Hartmut Ehrig; Horst Hansen; Michael Löwe (ADT, 1988)

Modular Algebraic Specifications. - Horst Hansen; Michael Löwe (ALP, 1988)

Categories for the Development of Algebraic Module Specifications. - Hartmut Ehrig; Werner Fey; Horst Hansen; Michael Löwe; Francesco Parisi-Presicce (Categorial Methods in Computer Science, 1988)

Algebraic Software Development Concepts for Module and Configuration Families. - Hartmut Ehrig; Werner Fey; Horst Hansen; Michael Löwe; Dean Jacobs (FSTTCS, 1989)

Algebraic Specification of Modules and Configuration Families. - Hartmut Ehrig; Werner Fey; Horst Hansen; Michael Löwe; Dean Jacobs; Anno Langen; Francesco Parisi-Presicce (J. Inf. Process. Cybern., 1989)

Compatibility Problems in the Development of Algebraic Module Specifications. - Hartmut Ehrig; Werner Fey; Horst Hansen; Michael Löwe; Dean Jacobs; Francesco Parisi-Presicce (Theor. Comput. Sci., 1990)

The PADKOM System Model - An Open Platform for Medical Applications in a Distributed Multimedia Environment. - Horst Hansen; Ralf-Detlef Kutsche; Joachim Steffens (Open Distributed Processing, 1991)

Medical Applications of ODP. - Horst Hansen; Ralf-Detlef Kutsche (Open Distributed Processing, 1993)