Ferraz, R. O. (2003). International education, qualification and certification systems in welding: International education, qualification and certification systems in welding = Međunarodni sustavi izobrazbe, kvalificiranja i ovlašćivanja u zavarivanju. Zavarivanje, p. 6.
Chicago stil citiranjaFerraz, R. Oliveira. "International education, qualification and certification systems in welding: International education, qualification and certification systems in welding = Međunarodni sustavi izobrazbe, kvalificiranja i ovlašćivanja u zavarivanju." 2003: 6.
MLA stil citiranjaFerraz, R. Oliveira. "International education, qualification and certification systems in welding: International education, qualification and certification systems in welding = Međunarodni sustavi izobrazbe, kvalificiranja i ovlašćivanja u zavarivanju." 2003: 6.