http://www.esec-j-gomes-ferreira.rcts.pt/ENTREVISTA%20H.%20Ferreira%20VA%2026.htm

http://riscos-ao-desafio.blogspot.com.es/2012/02/raul-hestnes-ferreira_29.html

http://pt.saint-gobain-glass.com/newsletter/2010_files/dez2010_02_home.html