• 

  Flora of North America: Volume 2: Pteridophytes and Gymnosperms - Google Books

  https://books.google.de/books?id=VnlBQMJOi-UC

  To be published in 14 volumes over the next 12 years, this long-awaited synoptic compendium represents the first and only comprehensive taxonomic guide to the extraordinary diversity of plant life blanketing our continent north of Mexico--including…

• 

  Flora of North America: North of Mexico - Flora of North America Editorial Committee - Google Books

  https://books.google.de/books?id=NURmQDm_dJsC

  To be published in 14 volumes over the next 12 years, this long-awaited synoptic compendium represents the first and only comprehensive taxonomic guide to the extraordinary diversity of plant life blanketing our continent north of Mexico--including…

• 

  Carl Ludwig Hübsch's DRIFT

  https://web.archive.org/web/20120309040112/http://www.clhuebsch.de/projects/drift.html

  Keine Beschreibung vorhanden.

• 

  Georg-August-Universität Göttingen - Prof. Dr. Peter Kappeler

  http://www.soziobio.uni-goettingen.de/kappeler.php

  Webseiten der Georg-August-Universität Göttingen

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