Some images in this post are copyright-protected. It is kindly advised that you edit your post and replace them with images under the appropriate license. For more information click on the link below.
https://steemit.com/steemstem/@steemstem/guidelines-on-copyright-standards-in-steemstem
I use one image and it was sourced directly below it. The source was a University website. The University website in turn sourced the image much the same as I did, linking it back to it's original.
Regardless, I've replaced the image with one from Wikipedia commons. Thanks.