- Google Scholar
https://scholar.google.com.hk/ - Kew record of Taxonomic literature
https://kbd.kew.org/kbd/searchpage.do - Taxonomic literature: a selective guide to botanical publications
https://www.biodiversitylibrary.org/item/103414#page/11/mode/1up - Hunt Institute for Botanical Documentation
https://huntbotanical.org/archives/?1 - The Contributions from the U.S. National Herbarium, Smithsonian Institution
https://botany.si.edu/pubs/cusnh/index.htm - Botanicus – historic literature
https://www.botanicus.org/browse - Biodiversity Heritage Library (BHL)
https://www.biodiversitylibrary.org - Taxonomic Literature (1753-1940)
https://www.sil.si.edu/digitalcollections/tl-2/ - Biblioteca Digital
https://bibdigital.rjb.csic.es/ing/index.php - JSTOR (archive of journals)
https://www.jstor.org - WorldCat
https://www.worldcat.org - Worldwide Science Sources
https://worldwidescience.org/index.html
School of Life Sciences, The Chinese University of Hong Kong