Kunkel, K. E., Andsager, K., Conner, G., Decker, W. L., Hillaker, H. J., Knox, P. N., Nurnberger, F. V., Rogers, J. C., Scheeringa, K., Wendland, W. M., Zandlo, J., Angel, J. R. (1998). An expanded digital daily database for climatic resources applications in the midwestern United States, Bull. Am. Meteor. Soc., 79 (7), 1357-1366