Environmental Health and Safety, Glossary, University of Chicago, Illinois, USA 2010. http://safety.uchicago.edu/tools/glossary.shtml, (Ergo - Amer) {753}
US Department of Labor, OSHA Construction eTool: Glossary (General Construction: electrical Incidents, Falls, Struck-By, Trenching And Excavation) Occupational Safety & Health Administration OSHA, Washington, D.C., USA 2010. https://www.osha.gov/SLTC/etools/construction/glos sary.html, (OSHA/Gen Const - Amer) {615}
US Department of Labor, Scaffolding eTool: Glossary, Occupational Safety & Health Administration OSHA, Washington, D.C., USA 2010. https://www.osha.gov/SLTC/etools/scaffolding/gloss ary.html, (OSHA/ Scaffolding - Amer) {619}