Biologist Beatrice Mintz (born in 1921) was a professor at the University of Chicago, 1946-1960, before joining the Institute for Cancer Research (now called the Fox Chase Cancer Center) and then becoming a professor at the University of Pennsylvania in 1965. Photo retrieved from Wikimedia Commons, no known copyright restrictions exist. No changes were made to the photo.

Graduation Ceremony at the University of Maryland (United States of America), 2014. Photo taken by Jay Baker, licensed under the terms of the cc-by-2.0 and retrieved from Wikimedia Commons. No changes were made to the photo.

Copper engraving of Johann Georg Puschner (alias “Dendrono”) of 1725: “The diligent student”. Retrieved from Wikimedia Commons. This work is in the public domain because its copyright period has expired. No changes were made to the work.

A panorama of a research room taken at the New York Public Library, 2006. Photo taken by Diliff, edited by Vassil, licensed under the terms of the cc-by-2.5 and retrieved from Wikimedia Commons. No changes were made to the photo.

Ibn Battuta (1304-1368/69) was a Muslim Berber Moroccan scholar and explorer who widely travelled the medieval world. Book illustration by Léon Benett published in 1878 showing Ibn Battuta (right) and his guide in Egypt. Retrieved from Wikimedia Commons. This work is in the public domain because its copyright period has expired. No changes were made to the work.

USAPHC Toxicology Lab technician assessing TOX samples, 2002. Photo taken by Ben Bunger, licensed under the terms of the cc-by-2.0 and retrieved from Wikimedia Commons. No changes were made to the photo.

Letter jumble. Photo taken by Bill Dickinson, licensed under the terms of the cc-by-nc-2.0 and retrieved from Flickr. No changes were made to the photo.