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WikiPedia: Hans Axel von Fersen http://cantic.bnc.cat/registres/CUCId/a11543486 http://catalogo.bne.es/uhtbin/authoritybrowse.cgi?... http://uli.nli.org.il/F/?func=direct&doc_number=00... http://data.bibliotheken.nl/id/thes/p06774334X https://books.google.com/books?id=DIkaAAAAYAAJ https://books.google.com/books?id=PWQFAAAACAAJ https://books.google.com/books?id=TzCMXzgl8kUC https://books.google.com/books?id=WPAtMCWLDz4C&pg=... https://books.google.com/books?id=bLJBAAAAIAAJ https://books.google.com/books?id=dFcAD6-0An4C