In fact these stories were already published in PILOT

As Petit Nicolas would say this book ... it's great! I am American, and I discovered Nicolas when I lived in France 15 years ago. I felt that I had read all of Nicolas and then this new collection is out. After reading the introduction of Anne Goscinny and also the negative comments about the origin of this news, I search a little deeper to better understand from where they came. It like they left one after the other every week in the magazine during the year PILOT 60. So now I do not understand why they are called unpublished stories. There is a huge webpage with a list of all titles released:

[...]

I now have the impression and feel about these unpublished stories are true.

What we lack now are the cartoons Petit Nicolas that appeared in a magazine or newspaper that was called The Mosquito ... during 50 years!

Thank you DD & R Goscinny Sempe for Nicolas !!

Sincerely,
John