Wagner, R.H. & Álvarez-Vázquez, C. 2010. The Carboniferous floras of the Iberian Peninsula: A synthesis with geological connotations. Review of Palaeobotany and Palynology, 162 (3), 238-324; doi:10.1016/j.revpalbo.2010.06.005.
Wagner, R.H. & Wagner-Gentis, C.H.T. 1952. Aportación al conocimiento de la geología de la zona de Barruelo (Palencia). Estudios Geológicos, VIII, 16, 301-344.
Wagner, R.H. & Winkler Prins, C.F. 1970. The stratigraphic succession, flora and fauna of Cantabrian and Stephanian A rocks at Barruelo (prov. Palencia), N.W. Spain. In: Colloque sur la Stratigraphie du Carbonifère (eds. Streel, M. & Wagner, R.H.). Congrès et Colloques de l’Université de Liège, 55, 487-551.
Wagner, R.H. & Winkler Prins, C.F. 1985. Stratotypes of the two lower Stephanian stages, Cantabrian and Barruelian. Compte Rendu 10e Congrès International de Stratigraphie et Géologie du Carbonifère, Madrid 1983, 4, 473-483.
Wagner, R.H. & Winkler Prins, C.F. 1985. The Cantabrian and Barruelian stratotypes: a summary of basin development and biostratigraphic information. In: Papers on the Carboniferous of the Iberian Peninsula (Sedimentology, Stratigraphy, Palaeontology, Tectonics and Geochronology) (eds. Lemos de Sousa, M.J. & Wagner, R.H.). Anais da Faculdade de Ciências do Porto, Supplement to Vol. 64 (1983), 359-410.
Wagner, R.H. & Winkler Prins, C.F. 2016. History and current status of the Pennsylvanian chronostratigraphic units: problems of definition and interregional correlation. Newsletter on Stratigraphy, 49/2, 281-320.
Wagner, R.H., Carballeira, J., Ambrose, T., López-Rico, J. & Martínez-García, E. 1984. Mapa Geológico de España, E. 1:50.000. Barruelo de Santullán (107), 1-113. Instituto Geológico y Minero de España, Madrid.