Book  (1951)  Page(s) 110.  
 
Griffith J. Buck.  Varieties of Rose Understocks.
Schmidt's Special.  This probably has had the same history as the two preceding selections.    [i.e. discarded]

Book  (1944)  Page(s) 18.  
 
George M. Taylor.  The Root Systems of Our Garden Roses.
The stocks now in general use, apart from the seedlings of R. canina which are used so indiscriminately are Brogs, Deegens, Jagerbataillon, Kokulensky, Senff, Schmidt's Ideal and Schmidt's Special.  They are all different strains of R. canina and were selected by Nurserymen in an endeavour to secure some attempt at uniformity.  It should be noted that these stocks are all of continental origin and are mainly from Holland. 

Book  (1936)  Page(s) 650.  
 
Schmid's Unterlagen (canina) found rose, Ideal and Rekord.
Schmidt's Unterlage Special (canina) J. C. Schmidt = Haller's Special.