1. Anon. ‘Zerstorungsfreie Schweissnahtprufung auf Baustellen’ (PLE-Norm 9002)
2. Anon. ‘Standard for welding pipelines and related facilities’, American Petroleum Institute, (API 1104)
3. Detection by radiography and ultrasonics of lack of fusion in welds in pipelines made by the CO2 process;Sterke;British Welding J,1967
4. Proposed assessment methods for flaws with respect to failure by brittle fracture;Anon;Welding in the World,1975