RHS Lily Register
https://www.rhs.org.uk/plants/pdfs/plant-register-supplements/Lilies/lily-register-and-checklist.pdf
https://www.rhs.org.uk/plants/pdfs/plant-register-supplements/Lilies/LilySupp1.pdf
https://www.rhs.org.uk/plants/pdfs/plant-register-supplements/Lilies/LilySupp2.pdf
https://www.rhs.org.uk/plants/pdfs/plant-register-supplements/Lilies/lilysupp3-(1).pdf
http://www.prairielily.ca/index_htm_files/lily-register-2007-4th.pdf
https://www.rhs.org.uk/plants/pdfs/plant-register-supplements/Lilies/Fifth-Lily-Supplement.pdf
Lilies in the Flora of China:
http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=118558
Native Species of the Genus Lilium and the Closely Related Nomocharis in Yunnan, China:
http://www.globalsciencebooks.info/Online/GSBOnline/images/2012/FOB_6(SI2)/FOB_6(SI2)28-38o.pdf
Lilies in the Flora of North America:
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=118558
U S Dept of Agriculture, useful species distribution maps:
https://plants.usda.gov/core/profile?symbol=LILIU
University of California, Berkeley, Jepson Flora:
http://ucjeps.berkeley.edu/cgi-bin/get_cpn.pl?LILIU
Taxonomic notes on Chinese Lilium L. (Liliaceae) with proposal of three nomenclatural revisions:
e-monocot (Lilium):
http://www.e-monocot.org/?q=lilium
Growing California Native Lilies:
https://www.pacifichorticulture.org/articles/growing-california-native-lilies