Result: If $X$ is a complete separable metric space then there is a $E \subset [0,1]^{\mathbb{N}}$ such that $X$ is homeomorphic to $E$ ($E$ is a $G_\delta$ set - is the intersection of denumerable open sets)
This result is used to prove theorem 2.3 of [PARTHASARATHY, 1967, Probability measures on metric spaces, pg 18]. and it is quoted as a well know result.
1) How to prove this result?
This result is to be found (according the author) in Kuratowski's 1933 book "Topologie I" pages 215-216. But I couldn't find it.
2) Could you indicate a good book where this result is to be found?