	Authors	Year	Title
	Wagner, Winkler_Prins & Riding	1971	Lithostratigraphic units of the lower part of the Carboniferous in Northern León, Spain [with a Note on some Goniatite Faunas by C.H.T. Wagner-Gentis]. Trabajos de Geología, 4: 603-663, fig.1-10, pl.1-3; Oviedo.