Precise Definition of the Single-Track Level Crossing in Radio-Based Operation in UML Notation and Specification of Safety Requirements. - Saeid Arabestani; Friedemann Bitsch; Jan-Tecker Gayen (SoftSpez Final Report, 2004)

OOLH: A Formal Framework for Specifying System Requirements. - Yuen Man Hon; Jan-Tecker Gayen; Hans-Dieter Ehrich (SIGSAND-EUROPE, 2008)