Article (magazine)  (Jan 1955)  Page(s) 20.  
 
In crimson to maroon, (Class V) , 'Koi-kagura,' 'Kasane-jishi,' and 'Konron-koku,' 'Hatsu-garashu,' 'Sumi-noichi,' and 'Kokko'.

Article (magazine)  (Jan 1955)  Page(s) 58.  
 
Alphabetical Check List of Tree Peony Names In  Public Collections And/or Available in Nurseries 1954-1955
Japanese, Crimson, 'Konron-koku' (Land of Konron) (Jap. bef. 1893), [Gardens] Scott Foundation, John J. Tyler Arboretum, [Nurseries] Oberlin Peony Gardens

Website/Catalog  (1949)  Page(s) 37.  
 
Peonies
Rare Tree Peonies (Nov. delivery)
Japanese Varieties. $8.50 each
Konron Koku (Land of Konron). Pansy-violet shaded maroon; double.

Website/Catalog  (1924)  Page(s) 152.  
 
Pivoines en arbre, du Japon...Kouronkoku.- Rouge pourpre.

Website/Catalog  (1909)  Page(s) 13.  
 
Paeonia Moutan...
30. Konron-koku, dark purple, 10 inches.

Website/Catalog  (1898)  Page(s) 11.  
 
PÆONIA MOUTAN. (Tree Peonies.)
30. Konron-koku, dark purple.