Book  (1936)  Page(s) 293.  
 
Gemen, Berthe (HP) Gemen 1899; glossy ivory-white, center pinkish white, very large, very double, imbricated, solitary, fragrance 6/10, firm stems, growth 5/10, dense.

Book  (1910)  Page(s) 279.  
 
Berthe Gemen flowers invory-white, large, full, and imbricated, fine in bud and half-open state.

Booklet  (1904)  Page(s) 20.  
 
Berthe Gemen  (Gemen & Bourg, 1898) Ivory-white, very large and full, perfect imbricated form, carrying flowers on stiff stems; a handsome and distinct variety. A sport from Marchioness of Dufferin. 

Magazine  (1899)  
 
Novelty for 1899
[...] Seedling of Marchioness of Dufferin