Specifications for the development of a fully three-dimensional numerical groundwater model for regional mass transport of radionuclides from a deep waste repository, report, April 1, 1980; (https://digital.library.unt.edu/ark:/67531/metadc1068121/m1/1/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .