About promoting an article written by B. Dobrescu and D. Lincoln
if I'm already talking about them why to put a reference

For readability, it is nice to have a list of the references at the end of the posts with links to the plain articles. For readers who want to know further.

I will say again, if the image that I add to the article i find in a, b, c, site these sites are my sources.

On some sites like the one you mention, anyone can upload anything, including copyrighted material. All the images you are using can be found on official websites. Therefore, it is preferable to use the sources from there. It is a bit more work for you, but that gives more credibility to your post. At least from the perspective of (some) readers (some of them working on what you are talking about).