Gutierrez-Marco, J.C., Loydell, D.K. and Storch, P. (2021) “The Silurian Section of the Valle syncline (Sierra Norte de Sevilla UNESCO Global Geopark, Spain) as an International Standard for Graptolite Biostratigraphy”, Geoconservation Research, 4(1). doi:10.30486/gcr.2020.1908691.1032.