F. K. Ligtenberg
- Structural safety and catastrophic events. Vorgetragen bei: IABSE Symposium: Symposium on Concepts of Safety of Structures and Methods of Design, London, United Kingdom, 1969. (1969):
- Some remarks concerning the introduction of Mr. G.R. Mitchell on "Loading on buildings". Vorgetragen bei: IABSE Symposium: Symposium on Concepts of Safety of Structures and Methods of Design, London, United Kingdom, 1969. (1969):
- La investigación sobre hormigón pretensado en Europa occidental. In: Hormigón y acero, v. 20, n. 92 (3. Quartal 1969). (1969):