I have found a company that specializes in nothing but Viburnums! They have a really nice page listing viburnums by name and its called the “Classic Viburnum Plant Library“. They do not have all viburnums listed on their site, but they have a lot of them. They also offer what looks like seedlings for sale, either wholesale or retail. I have added this wonderful resource to the Viburnum Bonsai page, under Deciduous Bonsai and Bonsai Tree Information.