I found an interesting French mathematics free resource website

The website is http://www.numdam.org/, which you can read and download the maths works of some mathematicians and their works published in French culture. Many of them are advantageous and need to be read as a French conjugate to English mathematical literature counterpart. It has many books published in 20th century and cover a wide range and some advanced topics such as homology theory, Lie groups, finite groups and K-theory.