Primary vs. Secondary sources
Source: YouTube, Hartness Library, 2017, Duration 3:17, URL: https://www.youtube.com/watch?v=gStyna348M0
Source: The Evolution of Scientific Information (from Encyclopedia of Library and Information Science, vol. 26).
Everything we know about physics in one neat infographic
Source: https://www.flickr.com/photos/95869671@N08/30976775430/in/dateposted-public/