1. The significance of trace fossils in sedimentology. Stratigraphy and palaeoecology with examples from the Lower Palaeozoic strata;Crimes,1970
2. Conodonts, conoidal shells of uncertain affinities, worms, trace fossils and Problematica;Häntzschel,1962
3. Trace fossils and problematica;Häntzschel,1975
4. Names based on trace fossils (ichnotaxa): request for a recommendation;Häntzschel;Z.N.(S.) 1973. Bull. Zool. Nomenclature,1972
5. Comments on the application concerning trace fossils;Lemcke;Z.N.(S.) 1973: Bull. Zool. Nomenclature,1973