[4] Like his father and brother before him, in 1904 Bohr enrolled at the University of Copenhagen, where he studied mathematics, obtaining his master's degree in 1909 and his doctorate a year later.

[6] A collaboration with Göttingen-based Edmund Landau resulted in the Bohr–Landau theorem, regarding the distribution of zeroes in zeta functions.

[9] In the 1930s Bohr was a leading critic of the anti-Semitic policies taking root in the German mathematical establishment, publishing an article criticising Ludwig Bieberbach's ideas in Berlingske Aften in 1934.

Harald was selected to play for the Denmark national team in the 1908 Summer Olympics, where football was an official event for the first time.

[13] Denmark faced hosts Great Britain in the final, but lost 2–0, and Bohr won a silver medal.

[16] Following the murder of Kaj Munk on 4 January 1944 the Danish resistance newspaper De frie Danske brought condemning reactions from influential Scandinavians, including Bohr.