Book  (Apr 1993)  Page(s) 475.  
 
Professor Gnau Hybrid Tea, white, 1928, 'Pskar Cordel' x Seedling; Tantau. Description.

Book  (1936)  Page(s) 304.  
 
Gnau, Professor (HT) Tantau 1928; O. Cordel X ?; matte cream-yellow, edges with matte red or pink reflexes, fades to white, medium-size, semi-double, ovoid to cup-form, lasting, solitary or up to 4, fragrance 7/10, floriferous, continuous bloom, long & strong stems, red thorns, light green branches, dense dark green foliage, large long & pointed buds, growwth 6/10, upright, hardy. Sangerhausen

Magazine  (1932)  Page(s) 20.  
 
I found 6 German rose nurseries represented with novelties: ....Math. Tantau with Urdh, Stämmler, Amulett, Professor Gnau, Johanniszauber and Johanna Tantau...