Book  (Jan 2000)  Page(s) 236.  
 
Gold Sovereign Hybrid Tree Peony. (Saunders 1949). A semi-double gold hybrid

Magazine  (Sep 1977)  Page(s) 20-21.  
 
"Botanical Descriptions of 40 Saunders Lutea Hybrids" by Dr. David Reath and Silvia Saunders
...These descriptions aim to provide the nurseryman and the average gardener with a means of determining the differences between the hybrids, many of which are very similar indeed...
Gold Sovereign—Semi-double medium-size blooms, clear yellow. Flares small and dark; heart otherwise all gold-and-cream. Filaments fine, uneven lengths. Anthers "naked". Stigmas cream; sheath cream.

Article (magazine)  (Jan 1955)  Page(s) 25.  
 
Varieties Raised in America. All by Professor Saunders...
The "Golden Hind Group." Yellow, clear or almost clear , generally semi- or fully double...
'Gold Sovereign,' (1950)

Article (magazine)  (Jan 1955)  Page(s) 57.  
 
Alphabetical Check List of Tree Peony Names In  Public Collections And/or Available in Nurseries 1954-1955
Lutea hybrid, Yellow, 'Gold Sovereign' (Saund. 1950)

Website/Catalog  (1949)  Page(s) [8].  
 
Hybrids Between Chinese Tree Peonies and P. Lutea or P. Delavayi
Gold Sovereign. (1949) Exquisite bright golden, flat double rosette. Very good and distinct.