http://tobaccodocuments.org/filters/1003285669-5696.html
Neurocommunications Research Lab; Dunn, W.L.; Houck, W.; Ryan, F.; Weinstein, C.; Weinstein, S. "THE EFFECT OF FILTER COVERAGE OF CIGARETTE VENTILATION HOLES UPON SMOKE DELIVERY". 14 Feb 1983. Bates: 1003285669-1003285696.
http://tobaccodocuments.org/filters/1003285669-5696.html