(1951). Conservation education in american schools: Twenty-ninth yearbook. Washington, D.C: American Association of School Administrators.
Παραπομπή Chicago StyleConservation Education in American Schools: Twenty-ninth Yearbook. Washington, D.C: American Association of School Administrators, 1951.
Παραπομπή MLAConservation Education in American Schools: Twenty-ninth Yearbook. Washington, D.C: American Association of School Administrators, 1951.
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