Brown, R.H., Ferris, J.G., Jacob, C.E., Knowles, D.B., Meyer, R.R., Skibitzke, H.E. and Theis, C.V., 1963, Methods of Determining Permeability, Transmissiblility and Drawdown (WSP-1536-I), 99 pp., 6 x 9 1/2. Description: The development of the nonequilibrium formula by Theis was a major advance in the field of ground-water hydraulics, and Wenzel did much to make the formula a practical too for the hydrologist. Black/White copy (reprint) available as this publication is out of print. Visit USGS.gov to download a free copy.