Michael F. Atiyah, Convexity and commuting Hamiltonians (1982), Theorem 1.
Michèle Audin, Torus actions on symplectic manifolds (2nd ed., 2004), Corollary IV.3.2.
Michael F. Atiyah, Convexity and commuting Hamiltonians (1982), Theorem 1.
Michèle Audin, Torus actions on symplectic manifolds (2nd ed., 2004), Corollary IV.3.2.