Hammond, J.P.; Slaughter, G.M. & Gurtner, F.B. HETEROGENEITY OF FUSION WELDS DETERMINED BY USE OF $sup 63$Ni-TAGGED FILLER METAL., report, October 31, 1972; (https://digital.library.unt.edu/ark:/67531/metadc1035220/m1/1/: accessed October 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .