Lindemann's proof that $e^{a}$ is transcendental if $a$ is a non-zero algebraic number.

Question

This question is not about lindemann-weierstrass theorem.

In the wikipedia page, it is written that von lindemann first proved the statement I mentioned in the title and later weierstrass generalized it.

There is a proof of lindermann-weierstrass theorem on the wikipedia page but I cannot find the proof of von lindemann's non-generalized statement.

So this question is a request to all the readers to give me the proof in the answers or link me to a site which has the proof.