Charpa, U. (2011). The Cambridge "Realgymnasiusm" and the "Freie Schule" London: Historical and philosophical remarks on Gerd Buchdahl and Karl R. Popper / Ulrich Charpa. Year Book / Leo Baeck Institute.
Chicago-viite (17. p.)Charpa, Ulrich. "The Cambridge "Realgymnasiusm" and the "Freie Schule" London: Historical and Philosophical Remarks on Gerd Buchdahl and Karl R. Popper / Ulrich Charpa." Year Book / Leo Baeck Institute 2011.
MLA-viite (8. p.)Charpa, Ulrich. "The Cambridge "Realgymnasiusm" and the "Freie Schule" London: Historical and Philosophical Remarks on Gerd Buchdahl and Karl R. Popper / Ulrich Charpa." Year Book / Leo Baeck Institute, 2011.
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