Book  (1988)  Page(s) 17.  
 
('Yu Ling Long'; 'Exquisite Jade') low and spreading … rosettes of 20 petals. .. Perhaps that is the nearest we shall now discover to the lost R. chinensis minima, ancestor of all true Miniatures… A few survived in Switzerland … [named for] their discoverer, Rouletii. All modern true miniatures come from them.