Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Franz Bücheler:

"

In 1856 Bücheler graduated from the University of Bonn with a dissertation on linguistic studies of the Emperor Claudius. He held professorships successively at Freiburg (associate professor in 1858, full professor in 1862), Greifswald (from 1866), and Bonn (1870 to 1906).[1] At Bonn, he worked closely with Hermann Usener (1834–1905).