I am looking for a book that will give me a good proof of The Differentiable Slice Theorem -
Suppose a compact Lie group $G$ acts smoothly on a manifold $M$. Then every orbit has a $G$-invarient tubular Neighbourhood. More precisely, there is a linear representation of $G_x$, the stabilizer of $x$, on a vector space $S$ so that $G {\times}_{G_x} S$, the twisted product, is a tubular neighbourhood of the orbit $G(x)$.
Thanks.