publication venue for Resource recommendation in social annotation systems: A linear-weighted hybrid approach 2012 Finite languages for the representation of finite graphs 1996 EDGE-LABEL CONTROLLED GRAPH-GRAMMARS 1990 HANDLE NLC GRAMMARS AND RE LANGUAGES 1987 CONTEXT FREE NORMAL SYSTEMS AND ETOL SYSTEMS 1983 ETOL SYSTEMS WITH RANK 1979 STRUCTURE OF DERIVATIONS IN DETERMINISTIC ETOL SYSTEMS 1978