In the context of The Virgin and Child with Saint Anne and Saint John the Baptist, explain the Works by others derived from the drawing of the Subject.
Although apparently not being developed into a painting by Leonardo, the drawing was used as a source for the paintings of others. 
A painting based on the cartoon was made by Bernardino Luini. He was a pupil of Leonardo. Its subject differs from Leonardo's in that it includes St. Joseph. Luini's painting now is in the Biblioteca Ambrosiana, in Milan.The figure of Pomona in Francesco Melzi's painting, Vertumnus and Pomona, that is held in the Gemäldegalerie in Berlin, is based on that of the Virgin in this cartoon by Leonardo. The similarity may be seen most distinctively in the head. Melzi was another one of da Vinci’s pupils, one who played a significant role in his life. He would become the literary executor of all of da Vinci's papers and whose curation of them, led to the preservation of many of them into book form. He also drew a portrait of da Vinci that is among the few confirmed images of him.
Milan Luini's painting Pomona Bernardino Luini cartoon Biblioteca Ambrosiana Francesco Melzi Vertumnus and Pomona Gemäldegalerie