Tob. Reporter, 1997, 124-6, p. 74, ISSN.0361-5693
"Ultra-light"-smoking filter
U.S. Patent 5,622,190 assigned to Philip Morris Inc., New York, New York, USA. A concentric smoking filter in which the peripheral filter medium is a fibrous tow, such as fibrous cellulose acetate tow, and the core filter medium is a web material,...