We had a preparatory drawing for this painting the other day; it is in the Musee D'Orsay:
http://www.musee-orsay.fr/en/collections/works-in-focus/painting/commentaire_id/rest-8943.html?tx_commentaire_pi1%5BpidLi%5D=509&tx_commentaire_pi1%5Bfrom%5D=841&cHash=145d771c76
