I tried to link with the html file name, but it works because they are on the same folder.
[Title](./this-is-the-file.html)
But it is possible that another article would appear on another folder because of the ARTICLE_URL pattern. Examples:
[Title 1](/2014/02/article1.html)
[Title 2](/2014/01/25/article2.html)
Is it possible to link your own articles with a reference to the slug ? Any other better solution than the generated HTML file name ?