Hi Yann and Michael

Bernard Flam only wrote about different archives in Paris. 

This archives only have documents about people who lived in Paris.
http://archives.paris.fr/r/123/archives-numerisees/

Birth records (until 1919), Marriages (until 1944), Death records (until 1986)
http://archives.paris.fr/r/124/etat-civil-de-paris/

census lists 1926, 1931, 1936; cemetery records; military records (WWI)
http://archives.paris.fr/r/126/sources-genealogiques-complementaires/

Declarations of deaths of soldiers of WWI and of the Foreign Legion
http://archives.paris.fr/r/125/fonds-judiciaires/

Nancy (Département Meurthe-et-Moselle) with census lists until 1936
http://archives.meurthe-et-moselle.fr/archives-en-ligne
Nancy (online newspaper archives)
https://kiosque.limedia.fr/

Forbach (Département Moselle)
http://www.archives57.com/index.php/recherches/archives-en-ligne
http://www.archives57.com/index.php/recherches/aide-a-la-recherche

Bry-Sur-Marne (Département Val de Marne) with census lists until 1936
http://archives.valdemarne.fr/r/4/archives-en-ligne/

Regards
Svenja