Book  (Apr 2001)  Page(s) 94, 95.  
 
Page 94: Weisse Margot Koster see 'White Margo Koster'
Page 95: White Margo Koster (Sport of 'Margo Koster') Polyantha 1939. Hybridist?

Book  (1990)  Page(s) 131.  Includes photo(s).
 
Weisse Margot Koster Polyantha 1939. Description. A sport of 'Margot Koster'. Flowers: white, cupped...

Website/Catalog  (1978)  Page(s) 22.  
 
Rosiers Pleureurs Hauteur : 180/200 cm - Sujets à isoler sur pelouses ... Margot Koster ®

Book  (1955)  Page(s) 116.  
 
'Margo Koster White'. Another sport of the original 'Parisian Rose', this time a white. Occasionally - as is often the case with sports the characteristics of the old Mother-plant strike through, and some of the blooms reveal an orange-red, red or pinkish striping. Tall.