I first heard about Gassian in the well known french magazines of the 70's,
Best, Extra and Rock'n'Folk. Most of his pictures were published in Best, and yeah
I liked them and I still like them.
I've watched my first Stones exhibition in 1983, Gassian was already there

Paris Catalogue 1983
There's a great book with most of his rock pictures
that you should try to catch if you find it

Inside there's one of my favorite shot of Charlie holding his hat at The Airport which has been used later for some bootlegs.
Beside
Tarlé, he's one of our best rock photographers
dcbaMerci pour tes liens, le catalogue me tente plus que le déplacement au vu de ce que tu décris, le shot de 1967 à l'olympia wow, jamais vu avant !
HMNStonesCave