J. Liddicoat, R. S. Coe, P. W. Lambert, H. E. Malde, y V. Steen-Mcintyre, «Paleomagnetic investigation of quaternary sediment at Tlapacoya, México and at Valsequillo, Puebla, México», Geofis Int, vol. 20, n.º 3, pp. 249–262, jul. 1981.