Book  (Jan 2000)  Page(s) 226, 231.  
 
Page 226: Flight of Cranes. See 'Renkaku'.
Page 231: Renkaku Tree Peony. ex Japan 1931. Also sold as 'Flight of Cranes'... white

Book  (1999)  Page(s) 138.  
 
Paeonia suffruticosa 'Renkaku', cv., 1972

Website/Catalog  (1956)  Page(s) [1].  
 
Japanese Tree Peonies
Renkaku (Flight of Cranes) Large white double—yellow center...$6.00

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) 59.  
 
Alphabetical Check List of Tree Peony Names In  Public Collections And/or Available in Nurseries 1954-1955
Japanese, White, 'Renkaku' (Flock of Cranes, or Flight of Cranes) (Jap. bef. 1931), [Gardens] Morton Arboretum, Scott Foundation, Whitnal Park Botanical Gardens, [Nurseries] Oberlin Peony Gardens

Website/Catalog  (1939)  Page(s) [1].  
 
Tree Peonies (Pæonia arborea)
Japanese Tree Peonies 
English translation in parentheses
52. Rein-Kahu (Flight of Cranes). Large; double; fragrant; pure white, with central cushion of golden anthers. Profuse bloomer... $5.00

Website/Catalog  (1932)  Page(s) [2].  
 
Tree Peony
Paeonia arborea
Japanese
Rein-Kahu (Flight of Cranes) Large, semi-double, pure white blooms with a central cushion of golden anthers, fragrant...$5.00 Each.

Website/Catalog  (1929)  Page(s) 6.  
 
Tree Peony Section 
Paeonia Arborea
3. Flight of Cranes. "Rein Kahu." Large, semi-double white with a delightful odor and a center of golden anthers.

Website/Catalog  (1926)  Page(s) 4.  
 
Tree Peony Section.
3. Flight of Cranes. Large, double white with a delightful odor and a center of golden anthers. $7.00.

Website/Catalog  (1924)  Page(s) 152.  
 
Pivoines en arbre, du Japon...Renkaku.- Blanc semi-double.