Baader, Sophia Meike (2004). "Froebel and the Rise of Educational Theory in the United States". Studies in Philosophy and Education. 23 (5–6): 427–444. doi:10.1007/s11217-004-4453-0. OCLC186848000.
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"Waldron Faulkner and His Influence at GW". The George Washington University. December 21, 2006. Diarsipkan dari versi asli tanggal July 19, 2011. Diakses tanggal January 4, 2010.Parameter |url-status= yang tidak diketahui akan diabaikan (bantuan)
"Maple Grove". Forest Preserve of DuPage County. Diarsipkan dari versi asli tanggal July 1, 2009. Diakses tanggal January 9, 2010.Parameter |url-status= yang tidak diketahui akan diabaikan (bantuan)
Baader, Sophia Meike (2004). "Froebel and the Rise of Educational Theory in the United States". Studies in Philosophy and Education. 23 (5–6): 427–444. doi:10.1007/s11217-004-4453-0. OCLC186848000.