Definition: In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.
Input: Passage: Dürer's father wears a dark shirt, russet coat and a black hat lined with fur. His skin is slack at the mouth and chin, and he has small, intelligent eyes, which Von Fircks describes as "dark and serious". Their curves echo those of the heavy lids beneath. His eyes are lined with crow's feet and shadowed with brown hatched paint. His facial features are built from brush strokes more typical of drawing than painting—at this young age Dürer was a far more skilled draughtsman than painter. Technical analysis carried out in 2013 by Dagmar Hirschfelder revealed a detailed background which was over-painted by the artist. The abandoned interior space consisted of a corner of a room with an arched window looking out to a countryside view. This type of interior can be traced to the Netherlandish tradition, and is rare in German portraiture of the period.
Albrecht the Elder's lips are thin and tightly pursed and his mouth is broad and down-turned, yet his features are those of a handsome man. Marcel Brion described him as appearing "mild and thoughtful", an impression reinforced by the uncomplicated design of the painting. This view is reinforced by the relative drabness or simplicity of his clothes, which seem intended to convey a reserved, ascetic piousness. Dürer presents his father more like a low-ranking  ecclesiastic than a tradesman: a calm, considerate and straightforward man dressed up in his best, albeit modest, clothes. After his father's death in 1502, Dürer wrote that Albrecht the Elder "passed his life in great toil and stern hard labour, having nothing for his support save what he earned with his hand for himself, his wife and his children ... He underwent manifold afflictions, trials and adversities. But he won just praise from all who knew him ... he was also of few words, and was a God-fearing man."Martin Conway describes the portrayal of a dignified man marked by a grave expression and deep "furrows ploughed by seventy years of labour and sorrow". Conway believed the strength of the portrait is in part achieved through Dürer's ability to convey this hardship, while at the same time presenting a man still imbued with traces of pride, and possessing "a kind old face". Noting the obvious affection between the father and son as well as the half smile of the older man, he wonders if that grin might have been born of Albrecht the Elder's satisfaction that his toil has been rewarded by a son of such talent, who was now about to set out on the world for his wanderjahr. A contributing factor to this pride is that Albrecht the Elder trained his son in his own profession, as a jeweller, but at one point came to regret the choice of apprenticeship as the younger man was so obviously suited to drawing and painting. However, his son learned many skills during that period and it gave him a discipline with his hands that became a defining factor of his work, especially in his ability as an engraver.
Output:
What is the name of the artist who over-painted the detailed background, which was revealed in technical analysis carried out in 2013?