Orto Botanico ed Herbarium Mediterraneum dell'Università di Palermo
OPTIMA
Società Botanica Italiana
Biblioteca digital del Real Jardin Botanico
Biodiversity Heritage Library
Botanicus Digital Library
Global Biodiversity Information Facility
Index Herbariorum
International Plant Names Index (IPNI)
Internet Directory for Botany
Kew record of Taxonomic Literature
Plant species descriptions published in seed lists (1800-1900)
Projecto Anthos
Tela Botanica