Schemm-Gregory, Mena. “A New Species of Filispirifer (Brachiopoda: Delthyridoidea) from the Dra Valley, Morocco (Lower Devonian)”. Zootaxa 1739, no. 1 (April 2, 2008): 53–68. Accessed April 30, 2025. https://mapress.com/zt/article/view/zootaxa.1739.1.4.