Helm, W. H.; Vigée-Lebrun, Louise-Elisabeth [Ill.]: Vigée-LeBrun 1755-1842: her life, works and friendships : with a catalogue raisonne of the artist's pictures : with a frontispiece in colours, 40 photogravure plates and other illustrations (London: Hutchinson & Co., 1915)

A USEFUL FRIEND 23
sit to so accomplished and charming a painter. One of her most useful
friends was the Due de Cosse (who was to become Due de Brissac on the
death of his father in 1784), the acknowledged lover of Madame du Barry.
He employed the young artist to copy a portrait of his mistress, as well
as to paint an original portrait of himself, and he also purchased several of
her early studies. His position as a distinguished leader in social affairs
enabled him to advertise her talents very fruitfully.