Arboretums:
        Raulston Arboretum at N. Carolina State University

Gardens:
        Heronswood Nursery

Horticultural organizations:
        American Rhododendron Society
        Perennial Plant Association

Mail Order Catalog:
        Wayside Gardens

Retail Garden Center:
        Classic Nursery
        Clear Creek Nursery
        Emery's Garden
        Sky Nursery

Trade organization:
        Amercan Nursery and Landscape Association
        Ohio Nursery and Landscape Association
        Oregon Association of Nurserymen
        Pennsylvania Association of Nurseryman Trade Show
        Washington State Nursery and Landscape Association

University Extension Service:
        Washington State University Extension Service

Wholesale Nursery:
        Osberton Nurseries