# Where was the Banach-Mazur Theorem originally published?

I would like to cite the original source for the Banach-Mazur Theorem that the space $\mathcal{C}([0,1])$ of continuous functions on the unit interval is universal for separable Banach spaces, i.e., that for every separable Banach space $X$ there is an isometric embedding $i\colon X\to\mathcal{C}([0,1])$. In the books on functional analysis I have there is no reference to the original proof of this result.

In short my question is: where was the Banach-Mazur Theorem published originally?