1[1]FHWA,Flexibility in Highway Design.Washington D.C.1992.
2[2]Joel Marshik,Lyle Renz.Preserving A Spirit of Place:U.s.Highway 93 on the Flathead Indian Reservation.University of California,Davis.2001.
3[3]Jackson,S.D.,C.R.Griffin.A Strategy for Mitigating Highway Impacts on Wildlife.Department of Natural Resources Conservation,University of Massachusetts,Amherst.2000.