Michael F. Atiyah, Convexity and commuting Hamiltonians (1982), Theorem 1.

Dusa McDuff and Dietmar Salamon, Introduction to symplectic topology (2nd ed., 1998), Lemmas 5.51 and 5.54.

Michèle Audin, Torus actions on symplectic manifolds (2nd ed., 2004), Corollary IV.3.2.

Michael F. Atiyah, Convexity and commuting Hamiltonians (1982), Lemma 2.3.

Dusa McDuff and Dietmar Salamon, Introduction to symplectic topology (2nd ed., 1998), Lemmas 5.51 and 5.54.

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.

Michael F. Atiyah, Convexity and commuting Hamiltonians (1982), Theorem 1.

Dusa McDuff and Dietmar Salamon, Introduction to symplectic topology (2nd ed., 1998), Lemmas 5.51 and 5.54.

Michèle Audin, Torus actions on symplectic manifolds (2nd ed., 2004), Corollary IV.3.2.