Maul, E.; Eibach, R. (June 1999). "Vitis International Variety Catalogue". Information and Coordination Centre for Biological Diversity (IBV) of the Federal Agency for Agriculture and Food (BLE), Deichmanns Aue 29, 53179 Bonn, Germany. Archived from the original on 27 April 2007. Retrieved 2007-04-29.
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"Vine's Cultivation". Instituto dos Vinhos do Douro e Porto. Retrieved 2007-04-29.
web.archive.org
Maul, E.; Eibach, R. (June 1999). "Vitis International Variety Catalogue". Information and Coordination Centre for Biological Diversity (IBV) of the Federal Agency for Agriculture and Food (BLE), Deichmanns Aue 29, 53179 Bonn, Germany. Archived from the original on 27 April 2007. Retrieved 2007-04-29.