New York: Simon & Schuster, ISBN 0-671-76492-6 (translation first published: London: Methuen, 1937; many later editions)* Santini, Piero (1936) "The Forward Impulse".
New York: Simon & Schuster, ISBN 0-671-76492-6 (translation first published: London: Methuen, 1937; many later editions)*Santini, Piero (1936) "The Forward Impulse".