It's filed as “Da Vinci [...], d'après”; which basically means “copied from Da Vinci”. When the name of the copyist isn't known, it's common to file the copy u

It's filed as “Da Vinci [...], d'après”; which basically means “copied from Da Vinci”. When the name of the copyist isn't known, it's common to file the copy under the name of the original artist – and with the “d'après” at the end not to break the alphabetical order.