Why are some of my article referenced on Scholar google, and some other ain't?

If I look for the articles of my review, some are correcly found by google scholar eg: Valenciennes sous Vichy | Mémoires du Cercle Archéologique et Historique de Valenciennes
and some ain’t, eg: http://www.histoire-valenciennes-cahv.fr/Memoires/index.php/Memoires/article/view/619

I wonder how to correct it, without re-entering every single article…

I tried the sitemap trick mentioned here: [OJS] Indexing journal system to Google Scholar

But our installation has so many articles that I have no way of tracking how it worked.

Make sure that you have google scholar plugin and duplin core plugin enabled.

In the end I think that the same thing applies to Google Scholar as the rest of Google: you basically never know how exactly google is indexing.

If they were not enable, nothing would be indexed

Wrong link above: [OJS] Indexing journal system to Google Scholar