Glacial geological evidence for the medieval warm period. Hong, Y.T., Jiang, H.B., Liu, T.S., Zhou, L.P., Beer, J., Li, H.D., Leng, X.T., Hong, B. and Qin, X.G. 2000. Huang, S. and Pollack, H.N. 1997. Late Quaternary temperature changes seen in world-wide continental heat flow measurements. Keigwin, L.D. 1996a.
Sedimentary record yields several centuries of data.
Keigwin, L.D. 1996b. The little ice age and the medieval warm period in the Sargasso Sea. Le Roy Ladurie, E. 1971. Leavitt, S.W. 1994. Major wet interval in White Mountains medieval warm period evidenced in delta 13 of bristlecone pine tree rings.