Website/Catalog  (1926)  Page(s) 55.  
 
Nelly Koster, blanc pâle. 

Website/Catalog  (1924)  Page(s) 107.  
 
Nelly Koster (Patens). Large fl. blanc pur nacré, anthères blanches.

Website/Catalog  (1912)  Page(s) 78.  
 
Summer and Autumn Clematis.
In bloom from July to October.
These flower upon the wood of the current year's growth, and should therefore be pruned to five or six eyes.  
Nellie Koster, white, large flower; a beautiful variety...  1s. 6d.