1967 - Montreal, Canada - Expo '67, (Universal and International Exhibition of 1967) the most successful Fair ever, drawing more than 50 million visitors.
... covered by US patents 3,726,146 (1973) and 5,353,655 (1994) by L.A. Mishler and US patent 5,800,311 (1998) by P.S.Chuang.
External links
www.gyrotwister.de ...