Some useful lily links for your reference:
Cam Lilies – Breeder and Seller of Species and Garden Hybrid Lilies – Mail order service
Van Diemen Quality Bulbs – Seller of a broad range of lilies – Mail order service
North American Lily Society has a very informative and frequently updated website.
RHS Lily Group is the main lily group in the UK
The North American Lily Society is the umbrella group for Liliums in Canada & USA.
Lilium Balticum is a very active lily group in Latvia.
The Genus Lilium is a website containing very useful and comprehensive information on Lilium Species
Further links will be added as soon as their operators give their permission.