Roberson, G.P.; Martz, H.E.; Decman, D.J.; Camp, D.C.; Azevedo, S.G. & Keto, E.R. Characterization of waste drums using nonintrusive active and passive computed tomography, article, August 1, 1994; (https://digital.library.unt.edu/ark:/67531/metadc674310/m1/1/: accessed November 21, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .