Sato, Tokiyuki, et al. “Late Pliocene Calcareous Nannofossil Paleobiogeography of the Pacific Ocean: Evidence for Glaciation at 2.75 Ma”. Revista Mexicana De Ciencias Geológicas, vol. 19, no. 3, June 2018, pp. 175-89, https://rmcg.geociencias.unam.mx/index.php/rmcg/article/view/964.