WAGNER, R. H. The stratigraphy and structure of the Ciñera-Matallana Coalfield (prov. León, N.W. Spain). Trabajos de Geología, [S. l.], v. 4, n. 4, p. 385-431, 1971. DOI: 10.17811/tdg.4.1971.385-431. Disponível em: https://reunido.uniovi.es/index.php/TDG/article/view/2683. Acesso em: 28 sep. 2022.