Weber, Reinhard. “How Old Is the Triassic Flora of Sonora and Tamaulipas and News on Leonardian Floras in Puebla and Hidalgo, Mexico”. Revista Mexicana De Ciencias Geológicas, vol. 14, no. 2, Jan. 2019, pp. 225-43, https://www.rmcg.unam.mx/index.php/rmcg/article/view/1148.