Anderson, R.W.; Deschamps, N.H.; Rexford, H.E. & Talbot, M. DEVELOPMENT OF THE SIREN CAPSULE, PHASE I., report, January 1, 1969; (https://digital.library.unt.edu/ark:/67531/metadc865392/m1/1/: accessed January 16, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .