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Dyfyniad Arddull ChicagoRowland, Val, and Ken Birkett. Personal Effectiveness for Teachers. Hertfordshire: Simon and Schuster, 1992.
Dyfyniad MLARowland, Val, and Ken Birkett. Personal Effectiveness for Teachers. Simon and Schuster, 1992.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.