(1968). Populations: A science unit for the primary grades (Trial ed.). Science Curriculum Improvement Study.
Dyfyniad Arddull ChicagoPopulations: A Science Unit for the Primary Grades. Trial ed. Berkeley, CA: Science Curriculum Improvement Study, 1968.
Dyfyniad MLAPopulations: A Science Unit for the Primary Grades. Trial ed. Science Curriculum Improvement Study, 1968.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.