Knight, John A, y Luis J Sardina. «An Emended and Amplified Description of Pecopteris Apicalis Knight, a Fern Morphospecies of Mid-Stephanian Age from NW Spain». Spanish Journal of Palaeontology 31, no. 1 (abril 25, 2020): 95–114. Accedido enero 10, 2025. https://pasquin.uv.es/index.php/sjpalaeontology/article/view/17141.