Scientific Manpower and Education. hearings before the United States House Committee on Science and Astronautics, Eighty-Sixth Congress, first session, on June 24, 25, 1959. Part 2, Census of Scientific and Technical Personnel :

Committee Serial No. 19. Continuation of hearings on development of accurate census of scientists and engineers already certified and in training, together with estimate of numbers required to satisfy future space-age needs.