1. Yang Ying Ping and Macnae James, An Apparatus and Method for Detecting an Object in a Medium [Journal]. - Australian Capital Territory : World Intellectual Property Organization, August 29, 2002. - WO 02/067015 A1.
2. Sothcott Peter, Buried Object Location [Journal]. - [s.l.] : Great Britian, July 4, 1984. - GB 2132357.
3. Blum D. W., Electric Field Signature Detection [Journal]. - Alexandria : United States Patent and Trademark Office, April 19, 2012. - US 2012/0092019 A1.
4. Hassanzadeh Reza [et al.], Electrostatic Field Gradient Sensor [Journal]. - Alexandria : United States Patent and Trademark Office, June 5, 1990. - US 4931740 A.
5. Dower Roger G., Apparatus for electrostatically imaging the surface of an object located nearby [Journal]. - Alexandria : United States Patent and Trademark Office, July 4, 1995. - US 5430381 A.