Every episode of our YouTube channel is researched, fact-checked, and cited. This page lists the sources and the image credits for each episode. All narration is original. Episodes 1–8 use only Public Domain or Creative Commons archival images, credited one by one below; from Episode 9 on, each episode describes its visuals.
Image licenses are Public Domain (PD), CC BY, or CC BY-SA as noted. Images are used unmodified except for cropping, color balance, and orientation correction for video. Later episodes also use news photographs credited on screen and original visuals and motion graphics made for the episode; each episode’s image credits say which.