1. Impulse radar soundings in permafrost;Annan;Radio Science,1976
2. Ballard, R.F., 1983. Electromagnetic (radar) techniques applied to cavity detection. U.S. Army Corps of Engineers Water Way Experimental Station Technical Report GL-83-1, Report 5, 90 pp.
3. Barr, G.L., 1993. Applications of ground penetrating radar methods in determining hydrogeologic conditions in a karst area, west-central Florida. U.S. Geol. Surv. Water-Resources Invest. Report 92-4141, 26 pp.
4. Interpretion of ground penetrating radar profiles in karst terrane;Beck,1988
5. Application of ground-penetrating radar methods in hydrogeologic studies;Beres;Ground Water,1991