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

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  (1939)  Page(s) [1].  
 
Tree Peonies (Pæonia arborea)
Japanese Tree Peonies 
English translation in parentheses
35. Gessekai (Lunar world). Pure white, crinkled petals. 12 to 15 inches in diameter. Strong grower, rare and beautiful... $20.00