Kirkwood، James K؛ Working Group (2005). "Report of the Independent Working Group on Snares"(PDF). UK Department for Environment, Food, and Rural Affairs (DEFRA). ص. 54 (section 2.7). مؤرشف من الأصل(PDF) في 2013-04-02. اطلع عليه بتاريخ 2012-11-24.
Kirkwood، James K؛ Working Group (2005). "Report of the Independent Working Group on Snares"(PDF). UK Department for Environment, Food, and Rural Affairs (DEFRA). ص. 54 (section 2.7). مؤرشف من الأصل(PDF) في 2013-04-02. اطلع عليه بتاريخ 2012-11-24.