Fresh proof has been found to support the theory that Leonardo da Vinci's Mona Lisa, seen here at the Louvre, was the wife of a Florence merchant, the head of the library of Germany's Heidelberg University said on Tuesday.

Germany's University of Heidelberg says a researcher has uncovered evidence that apparently confirms the identity of the woman behind the Mona Lisa's famous smile.

She is Lisa del Giocondo, wife of Florentine businessman Francesco del Giocondo, according to notes written in the margins of a 1503 book by a friend of Leonardo da Vinci as the artist worked on the masterpiece, the school said in a statement.

The discovery by a Heidelberg University library manuscript expert appears to confirm what has long been suspected.

Del Giocondo was first named as the likeness in the painting by Italian writer Giorgio Vasari in 1550, who also dated the work at between 1503 and 1506, the university said.

But because Vasari relied on anecdotal evidence, there was always doubts about the identification, and Leonardo is not known to have made any notes about the model's identity himself.

"One possibility discussed is the presentation of a fictitious likeness of a woman; Leonardo's female ideal," the school said.

But the finding by Heidelberg library expert Armin Schlechter settles the matter, according to the university.

In a copy of the works of Roman philosopher Cicero, Agostino Vespucci, a Florentine official and friend of Leonardo's, wrote in the margins that da Vinci was working on a portrait of Lisa del Giocondo. He dated his notes October 1503, also helping pin down the exact time Leonardo was working on the painting.

"All doubts as to the identity of the Mona Lisa are eliminated （by） one source," the university said.

The discovery was actually made in 2005, but was not widely known until a German radio station last week aired it in a report.

传世画作《蒙娜丽莎》中那个带着神秘微笑的女子究竟是谁？德国海德堡大学近日称，一名研究人员发现了足以证实“蒙娜丽莎”身份的确凿证据。

德国海德堡大学在一份声明中说，研究人员在一本1503年的书中发现了达·芬奇的一个朋友的笔记。根据该笔记可以断定，画中的女子是佛罗伦萨商人弗朗西斯科·德尔·乔贡德的妻子丽莎·德尔·乔贡德。当时达·芬奇正在创作《蒙娜丽莎》这幅画。

海德堡大学一位图书馆笔迹专家发现的这一证据似乎可以证实人们长期以来的猜测。

据海德堡大学介绍，意大利作家乔治亚·瓦萨尼曾于1550年得出类似结论，同时他也认为《蒙娜丽莎》创作于1503年至1506年间。

但由于瓦萨尼的结论缺乏确凿的证据，这个说法一直受到怀疑。而达·芬奇本人也未对画中女子的真实身份进行过任何确认。

海德堡大学称：“有人猜测画中女子并没有现实原型，只是达·芬奇心目中的理想女性形象而已。”

而海德堡大学图书馆专家阿迈恩·施勒希特的这一发现解开了所有谜团。

这本书是古罗马哲学家西塞罗的一本著作。根据达·芬奇的朋友、佛罗伦萨官员阿戈斯蒂诺·韦斯普奇在书中空白处的留言，当时达芬奇正在创作丽莎·乔贡德的一幅画像。留言所注的日期为1503年10月，由此可以确定达·芬奇创作这幅画的具体时间。

海德堡大学称：“这个发现解开了所有有关蒙娜丽莎身份的谜团。”

其实这个证据在2005年就被发现了，但直到上周一家德国广播电台上星期公布这个发现后，更多的人才了解真相。