1. Le Bassin Houiller Lorrain peut-il fournir un stratotype pour le Westphalien supérieur?;Alpern;Rev. Palaeobot. Palynol.,1967
2. Use of series subdivisions of the Mississippian and Pennsylvanian Systems in reports by members of the U.S. Geological Survey;Bradley;Bull. Am. Assoc. Pet. Geol.,1956
3. Correlation of Carboniferous strata using a hierarchy of transgressive-regressive units;Busch;Geology,1984
4. Palynological evidence for a Pennsylvanian age assignment of the Dunkard group in the Appalachian Basin - Part II. W. Va. Geol. Econ. Surv.;Clendening;Coal-Geol. Bull.,1974
5. Morphology and systematics of cordaites of Pennsylvanian Coal Swamps in Euramerica;Costanza,1983