Journal Articles Mary C. Hill Analysis of intermediate-scale tracer experiments for the development of tracer density guidelines in heterogeneous porous media Barth, G.R., Illangasekare, T.H, Hill, M.C., and Rajaram, Harihar 2001, Water Resources Research, vol. 37, no. 1, p. 21-31 mchill@usgs.gov Last Modified: August 14, 2000