Book Cover

The original picture was taken from here: https://www.flickr.com/photos/138248475@N03/25801339423

And the Creative commons link is here:

https://creativecommons.org/licenses/by/2.0/

It states that you are free to:

Share — copy and redistribute the material in any medium or format

Adapt — remix, transform, and build upon the material

for any purpose, even commercially.