Einstein's future wife, Mileva Marić, also enrolled at the Polytechnic that same year, the only woman among the six students in the mathematics and physics section of the teaching diploma course. Over the next few years, Einstein and Marić's friendship developed into romance, and they read books together on extra-curricular physics in which Einstein was taking an increasing interest. In 1900, Einstein was awarded the Zurich Polytechnic teaching diploma, but Marić failed the examination with a poor grade in the mathematics component, theory of functions.^[27] There have been claims that Marić collaborated with Einstein on his celebrated 1905 papers,^[28][29] but historians of physics who have studied the issue find no evidence that she made any substantive contributions.^{[30][31][32][33]}