Hurd, P. D. (1969). New Directions in teaching secondary school science. Rand McNally.
Chicago-čujuhus (17. p.)Hurd, Paul Dehart. New Directions in Teaching Secondary School Science. Chicago: Rand McNally, 1969.
MLA-čujuhus (9. p.)Hurd, Paul Dehart. New Directions in Teaching Secondary School Science. Rand McNally, 1969.
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