1. Annan , A. P. Time-domain reflectometry-Air-gap problem in a coaxial line Report of Activities, Part B 55 58 Ottawa 1977
2. High-frequency electrical methods for the detection of freeze-thaw interfaces;Annan;Proc. Third Int. Conf. Permafrost,1978
3. Cihlar , J. F. T. Ulaby Dielectric properties of soils as a function of moisture content Lawrence, Kansas 1974
4. Davis , B. R. J. L. Lundien A. N. Williamson Feasibility study of the use of radar to detect surface and ground water Vicksburg, Miss. 1966