Fair use in
Leonardo, the Terrible Monster, taken from the requisite listing at Amazon.com, which was provided to them by the requisite holder of the distribution license:
It is of a lower resolution than the original, and will not affect the ability to market or profit off of the book.
No free images of or representative of the book can be found, and does not infringe on the rights of the holders of the copyright, who either produced the image or owns the rights to the item this image illustrates, and is the source for the original said copyrighted image.
The image is used on a variety of websites, thus not making it significantly more accessible or visible than it already is. The book image is being used for informational purposes only, and its use is not believed to detract from the original in any way.
Summary
Cover for "Leonardo, the Terrible Monster"
Licensing
This image is of book cover(s), and the copyright for it is most likely owned either by the artist who created the cover(s) or the publisher of the book(s). It is believed that the use of low-resolution images of book covers
to illustrate an article discussing the book in question