All chart images in one .zip released in cc0 license.
author:     O. Philip Martin
web-link:   https://www.opmartin.com/cc0/all-charts.zip
cc0-link:   https://creativecommons.org/publicdomain/zero/1.0/
host-site:  https://www.opmartin.com/
We believe the content which has been borrowed is covered under fair use.
 - 7-big-questions chart includes quotes from Robert Jeffress (c) 2019,
    and Erwin Lutzer (c) 2015
 - chalkboard-temperaments chart contains free image from Daniel Reche from Pexels
 - cosis chart contains images (c) by Kieran Heather
 - instrument-classification chart contains free images from OpenClipart-Vectors, Clker-Free-Vector-Images, and davidswidjaja, via Pixabay
 - trolls chart contains images (c) Dreamworks, and free quotes from Wikipedia
All other content is free to use under cc0.

