Thanks. Looking moreover, I found this plugin which is genius! It solved my question. And in fact, even if it’s not in the options of the plugin, you can sort alphabetically the articles’ title listed in the sticked article with a little string explained on the download page. Really cool.
http://redalt.com/wiki/Adhesive
I am using this plugin with this one :
http://www.sns.ias.edu/~cjm/wp/wordpress/posts-in-category/
