Google's link systems use links "to determine what pages are about", so links from relevant pages in your field are the ones it interprets best. The claim that a link in a 1,000-word post beats one in a short snippet is unconfirmed; Google says "the length of the content alone doesn't matter for ranking purposes." Main-content links outweighing footer links is plausible but unpublished. Wikipedia marks external links rel="nofollow", so a citation there brings readers, not reliable ranking credit.