Call me old-fashioned, but the book with Filliozat's article is still for sale with the publisher.

On Tue, 17 Nov 2020 at 02:40, Matthew Kapstein via INDOLOGY <indology@list.indology.info> wrote:

A brief but important study is Filliozat's:

https://indianmedicine.eldoc.ub.rug.nl/33562/

Unfortunately, a pdf does not seem to be readily available.