# Reference request; perfect graphs

Is it true that for perfect graphs the following holds:

A maximum size of an independent set in a graph $$G$$ equals to the chromatic number of $$\overline{G}$$, where $$\overline{G}$$ is the complement of $$G$$ of course.

If yes, what would be the reference?

By the perfect graph theorem (conjectured by Claude Berge in 1961 and proved by László Lovász in 1972 [L]), a graph is perfect iff its complement is perfect. Therefore a chromatic number of $$\overline{G}$$ equals to its clique number, which equals to an independence number of $$G$$.