1. The filtration of aerosols by fibrous electret filters;van Turnhout;Central laboratory Report,1969
2. Electret fibres for high-efficiency filtration of polluted gases;van Turnhout;Staub,1976
3. Manufacture and use of felt pads made from extremely fine fibres for filtering processes;Schmidt;Melliand Textilber,1980
4. New method of manufacturing non wovens by electrostatic laying, Advances in web forming;Trouilhet,1981
5. Method for the manufactures of smoke filters or collective filters;Hansen;British Patent BP 384052,1931