Plant collectors generally took plants when the species were at their peak flowering, as this provided the best taxonomic reference for the herbarium.

Zoological Record a database of animal biology and taxonomic reference (unofficial register of animal names).

Mammal Species of the World: a taxonomic and geographic reference.

While the Balkan lynx is listed as a subspecies in much of the news coverage and taxonomic references, there has been some dispute over those claims.

Mammal species of the world: a taxonomic and geographic reference.