Book  (1936)  Page(s) 381.  
 
Karl Eduard, Herzog (HT) Welter-Jacobs 1909; C. Testout X Farbenkönigin; bright cherry-red, center darker, large to very large, very double, fine form, solitary, fragrance 7/10, floriferous, repeats well, long upright stems, growth 7/10, upright

Magazine  (17 May 1911)  Page(s) 290.  
 
The Parentage of Roses.
The following list of the world's Roses and their parentage has been compiled by Mr. Robert Daniel, 38 Russell Road. Fishponds, Bristol, and by his kind permission we are enabled to publish it...
Herzog Carl Eduard [sic]... Hybrid Tea, Welter, 1909, Seedling Caroline Testout X Farbenkönigin