The Borel localization theorem in (Borel) equivariant cohomology states that if $T$ is a torus and $M$ a smooth $T$-manifold, with fixed point set $M^T$, then upon localizing the coefficient ring $H^*_T := H^*(BT)$ (that is, tensoring with its field of fractions), the restriction map $$H^*_T(M) \to H^*_T(M^T)$$ becomes an isomorphism.

The earliest reference to this result I know of is in Hsiang Wu-Yi's classic book on transformation groups, where he refers to the result as a "localization theorem of Borel–Atiyah–Segal type." It seems from Hsiang's presentation that Borel only proved this result for $T = S^1$; in any event, I've never been able to find the more general result in the *Seminar on Transformation Groups*. But I'd like to attribute it to **someone**.

**Who originated this result? Failing that, what is the earliest citation you know?**