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Dyfyniad Arddull ChicagoUnesco. UNEP International Environmental Programme, Thomas J. Marcinkowski, Trudi L. Volk, and Harold R. Hungerford. An Environmental Education Approach to Training of Middle Level Teachers: A Prototype Programme. Paris: Unesco, 1990.
Dyfyniad MLAUnesco. UNEP International Environmental Programme, et al. An Environmental Education Approach to Training of Middle Level Teachers: A Prototype Programme. Unesco, 1990.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.