http://webapps.rrc.state.tx.us/DP/drillDownQueryAction.do?fromPublicQuery=Y&name=DD&univDocNo=488978065
http://webapps.rrc.state.tx.us/DP/drillDownQueryAction.do?fromPublicQuery=Y&name=DD&univDocNo=488978066
http://en.wikipedia.org/wiki/Cathodic_protection