Emilie Vouga (née Pradès) was a Swiss painter of flowers and birds. Her flower paintings are still popular as posters today.
Colvert and Robert Wirth were Prussian-born engravers who were working in New York City as early as 1860. The firm Wirths Bros. & Owen also produced Christmas cards.
Bénézit, E. Dictionnaire critique et documentaire des Peintres, Sculpteurs, Dessinateurs et Graveurs. France : Librairie Gründ, 1966. Vol. 8. (Vouga)
Groce, George C. and Wallace, David H. The New-York Historical Society’s Dictionary of Artists in America 1564-1860. New Haven: Yale University Press, 1969. p. 697. (Wirth)