Barragán-Manzo R, Méndez-Franco AL. Towards a standard ammonite zonation for the Aptian (Lower Cretaceous) of northern Mexico. revmexcg [Internet]. 2018 May 7 [cited 2025 May 2];22(1):39-47. Available from: https://www.rmcg.unam.mx/index.php/rmcg/article/view/872