Book  (1928)  Page(s) 61.  
 
Check List of Japanese Peonies
Neptune. (Terry.) 6.0 (Sym. 1921). Pink. Discarded.

NB: Terry's 'Neptune' is here confused with the Japanese peony of the same name.

Website/Catalog  (1923)  Page(s) 8.  
 
Japanese Peonies
Neptune. Shell pink...$1.00

Book  (1907)  Page(s) 157.  
 
1782. NEPTUNE; P.
(1) 1904, Harrison's Paeony Manual, p.53.
(2) 1906, J. F. Rosenfield's Cat.

Book  (1907)  Page(s) 49.  
 
Japanese Peonies...
Neptune. A fine shell pink.

Book  (1904)  Page(s) 53.  
 
The Japanese Paeonys.
I append Henry Dreer's list:
Neptune. A fine shell pink.

Website/Catalog  (1903)  Page(s) 24.  
 
Japanese Single-flowering Herbaceous Pæonies.
No other plant flowering at the same season can vie with the Single Pæony for beauty, and an established bed, when in full bloom, with the large, silky flowers measuring from 6 to 7 inches across, and appearing like immense single Roses, is simply gorgeous.
Neptune. A fine shell pink.

Website/Catalog  (1901)  Page(s) 169.  
 
Japanese Single-flowering Herbaceous Pæonies.
The collection of twelve sorts offered below were selected for us by a reliable Japanese house, and we are assured contains the finest varieties in cultivation. 35 cents each; $3.50 per dozen.
Neptune. A fine pink.