1. Wallis, P.J.L.: ‘Numerical Software Portability and the PPL Project’, Hennell, M.A., Delves, L.M., Performance and Assessment of Numerical Software, (Academic Press p. 199–210
2. July, 1980 US DEPARTMENT OF DEFENSE: 'Reference manual for the Ada programming language'
3. Wichmann, B.A.: Tutorial Material on the Real Data-Types in Ada, (US Army European Research Office, London 1981 January)
4. Softech, INC.: 'Ada compiler validation implementers' Guide,1067–2.3, 1st October, 1980