Cahier n°21

https://sites.google.com/site/genearix/publications/les-cahiers/cahier-n-21/Cahier%20n%C2%B021b.jpg?attredirects=0
https://sites.google.com/site/genearix/publications/les-cahiers/cahier-n-21/Cahier%20n%C2%B021c.jpg?attredirects=0