1. http://www.corrosion.org/images_index/nowisthetime.pdf
2. http://nvl.nist.gov/pub/nistpubs/jres/115/5/V115.N05.A05.pdf.
3. http://www.oildompublishing.com/pgj/pgjarchive/March03/corrosioncosts3-03.pdf.
4. htpp://primis.phmsa.dot.gov/comm/reports/safety/sida.html?nocache=6853.