Projections of Orbits and Asymptotic Behavior of Multiplicities for Compact Connected Lie Groups. G.J. Heckman — 1982 Inventiones mathematicae
An elementary approach to the hypergeometric shift operators of Opdam. G.J. Heckman — 1991 Inventiones mathematicae
On the Variation in the Cohomology of the Symplectic Form of the Reduced Phase Space. J.J. Duistermaat; G.J. Heckman — 1982 Inventiones mathematicae
Addendum to "On the Variation in the Cohomology of the Symplectic Form of the Reduced Phase Space." J.J. Duistermaat; G.J. Heckman — 1983 Inventiones mathematicae