Self-Reference as a Principle Indicator of Complexity. - Stefan Hempel; Ricardo Pineda; Eric Smith (ICSEng, 2011)

Self-reference as a principal indicator of complexity. - Stefan Hempel; Ricardo Pineda; Eric Smith (Complex Adaptive Systems, 2011)

Specifying Life Cycle Requirements in a Natural-like Language and ptLTL. - Dominik Franke; Stefan Hempel; Stefan Kowalewski (ICST Workshops, 2013)