00277nam a2200097Ia 450000500170000000800410001708200140005810000250007224500520009726000300014920260205095209.0260111s9999||||xx |||||||||||||| ||und||  a371 B255U  aBarnard, J. Darrell. 2aA unified program in science, health and safety  aNew YorkbMacmillanc1959