Book  (Jan 2000)  Page(s) 227.  
 
Gessekai Tree Peony. ex Japan [no date given]. Also sold as 'Kingdom of the Moon'... white

Website/Catalog  (1956)  Page(s) [1].  
 
Japanese Tree Peonies
Gessekai (Kingdom of the Moon) Immense double white...$8.00

Article (magazine)  (Jan 1955)  Page(s) 20.  
 
In white, (Class I, of the American Peony Society), there are 'Gessekai,' 'Godaishu,' 'Fugi-oe-ryo,' 'Renkaku,' and 'Yaso-okina,' which are pure white throughout, 'Ima-chowkow,' which is creamy, and 'Kogane-zome' and 'Shuchiuka,' with pinkish and purplish splashes.

Article (magazine)  (Jan 1955)  Page(s) 57.  
 
Alphabetical Check List of Tree Peony Names In  Public Collections And/or Available in Nurseries 1954-1955
'Gessekai'

Website/Catalog  (1941)  Page(s) [3].  
 
Tree Peonies
Gessekai (Lunar World). Best; rare and beautiful; pure white; 12 to 15 inches in diameter; crinkled petals. Strong grower...$20 00

Website/Catalog  (1940)  Page(s) 13.  
 
New & Rare Varieties...
Gessekai, Pure white, shrinks on all petals, strong growing, largest among peonies usully 12-15 inches in diameter ...Each $ 1.30

Website/Catalog  (1940)  Page(s) 7.  
 
Japanese Tree Peonies 
English translation in parentheses
60. Gessekai (Lunar world). Pure white, crinkled petals. 12 to 15 inches in diameter. Strong grower, rare and beautiful. Best white...$20.00