== Diagrams ==

[[https://www.flickr.com/photos/britishlibrary/|British Library Flickr]]. Lots of black and white diagrams.

== Photography ==

[[https://www.pexels.com/|Pexels]]: Creative Commons Zero (CC0)-licensed stock photography

[[https://www.freestockimages.ru/free-images|FreeStockImages.RU]]: Russian-oriented free stock images.

== Videos ==

[[http://www.coverr.co/|coverr]]: Looping stock videos for Web pages