Our changing landscape: Indiana Dunes National Lakeshore / C.L.Hill,B.J.Ryan,B.A.McGregor,M.Rust, 1991. - VI,44 p. p. - Текст : непосредственный.
Ryan B.J. Results of hydrologic research at a low-level radioactive-waste disposal site near Sheffield, Illinois / B.J.Ryan, 1991. - 73 p. - Текст : непосредственный.