Liddicoat, J., Coe , R. S., Lambert, P. W., Malde, H. E., & Steen-Mcintyre, V. (1981). Paleomagnetic investigation of quaternary sediment at Tlapacoya, México and at Valsequillo, Puebla, México. Geofisica Internacional, 20(3), 249–262. https://doi.org/10.22201/igeof.00167169p.1981.20.3.1089