1. The Safety of Structures," by Alfred M. Freudenthal, Transactions;ASCE,1947
2. "Reflections on Standard Specifications for Structural Design " by Alfred M. Freudenthal ibid. Vol. 113 1948 p. 269.
3. "Concepts of Safety in Structural Engineering " by A. G. Pugsley Proceedings Inst. of C. E. London Vol. 29 1951.
4. "Conceptions Modernes Relatives a la Securite des Constructions " by M. Prot and R. Levi Revue Generale des Chemins de Fer June 1951.
5. (S) "Determination del Coefficiente de Seguridad en las Distintas Obras " by A. P. Balaca and E. Torroja Instituto Tecnico de la Construcci 6n Madrid 1950.