Gray, Esther. "Orff- Schulwerk: Where Did it Come From?" The Orff Beat-Centenary Issue XXIV (June 1995). Victorian Orff Schulwerk Association. 3 May 2009 <"A Brief History of Orff". Archived from the original on 15 September 2009. Retrieved 3 May 2009.>
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Gray, Esther. "Orff- Schulwerk: Where Did it Come From?" The Orff Beat-Centenary Issue XXIV (June 1995). Victorian Orff Schulwerk Association. 3 May 2009 <"A Brief History of Orff". Archived from the original on 15 September 2009. Retrieved 3 May 2009.>