Helicopters and VTOL aircraft work like this /
Arkell, Basil.
Taylor, John William Ransom.
Wood, John W.(John William),1926-
Hobson, William.
Cook, Frederick G.
London Dent
1972
Previous ed. published as 'Helicopters work like this'. London: Phoenix House, 1965
Includes index
Helicopters.
Vertically rising aeroplanes.