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Churchill, Daniel (2007). "Towards a useful classification of learning objects". Educational Technology Research and Development. 55 (5): 479–497. doi:10.1007/s11423-006-9000-y. S2CID57223598.
Beck, Robert J., "What Are Learning Objects?", Learning Objects, Center for International Education, University of Wisconsin-Milwaukee, archived from the original on 2010-07-04, retrieved 2008-04-29
Beck, Robert J., "What Are Learning Objects?", Learning Objects, Center for International Education, University of Wisconsin-Milwaukee, archived from the original on 2010-07-04, retrieved 2008-04-29