Ugochukwu, A. E. ., I. O. . Minapuye, and S.-O. . Geoffrey Chijioke. “Late Eocene to Early Miocene Biostragraphy and Palaeoenvironments in the Beta Field of the Northern-Central Niger Delta, Nigeria”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 62, no. 1, Dec. 2019, pp. 145-71, https://asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/4531.