Book  (2018)  Page(s) 155.  
 
Christen won the silver medal at a show in Paris in 1892 for displaying twenty-five varieties of clematis. He also entered shows in other parts of the country, such as the one held by Lyon Horticole in Lyon, where he displayed Clematis 'Papa Christen', 'Madame Boselli', and 'Eugene Delattre'.

Book  (1898)  Page(s) 62.  
 
Variétés Horticoles
1er Groupe.—PATENS
Section II. — Lanuginosa.
Eugène Delattre (Christen).  Belle fleur bleu lavande, de forme parfaite.