Below are links to free stoic texts from Project Gutenberg.
The Enchiridion by Epictetus
Discourses with The Enchiridion by Epictetus
Below’s link is provided by the Internet Archive.
On the Shortness of Life by Seneca
Below are links to the moral letters of Seneca prepared by Tim Ferriss.
The Tao of Seneca – Volume I, II, III by Seneca, Presented/Prepared by Tim Ferriss