Book  (Jan 2000)  Page(s) 236.  
 
Hesperus Hybrid Tree Peony (Saunders 1948). A 'Thunderbolt' cross. A single pink

Magazine  (Sep 1977)  Page(s) 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...
Hesperus—Single; 10-16 petals, rosy red, with golden tones, deeper at edges. Very finished flower, very similar to Renown. Like Renown, a rebloomer. Flares none; filaments short, dull crimson, darker than the petals. Stigmas bright pink; sheath crimson, darker than the petals.

Article (magazine)  (Jan 1955)  Page(s) 25.  
 
Varieties Raised in America. All by Professor Saunders...
The "Banquet Group." Generally reddish, but with yellow undertone, single to double...
'Hesperus,' (1948-1950)

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, 'Hesperus' (Saund. 1948-1950), [Gardens] MOrton Arboretum, Scott Foundation

Magazine  (Mar 1954)  Page(s) 22.  
 
Hybrid Tree Peonies
...By far the most important work with these hybrids has been done by Prof. A. P. Saunders and his originations now number about 80. Their color range is truly remarkable. [...]
The list of hybrid tree peonies following is up to date as far as we could make it.
Originations of A. P. Saunders, Clinton, N.Y.
Hybrids of suggruticosa, lutea and Delavayi.
Hesperus, Semi-double, pale yellow and rose. 1948.