Ur article is well written and quite interesting... U cited ur images, thats really good.. But I would like to mention that ur images are CC BY-SA 3.0 licensed which requires the attribution of following,

You must give appropriate credit, provide a link to the license, and indicate if changes were made.

I would suggest u to add the author name and license page link under ur images, that would make ur image citation perfect.
To learn more about image issues, take a look at this article.

Good day...!

~ Christina