International Patents
Germany:DE2555140A1
France:FR2295266A1
Sweden:SE408722B
Italy:IT1054674B
Japan:JPS5186810A
Canada:CA1038836A
United States:US3973469A
United Kingdom:GB1515138
Smoke intake and output as demonstrated at the United States of America Patent Office
NASA June 1990 tech brief copies John Humen