Optimality conditions for non-finite valued convex composite functions. - James V. Burke; R. A. Poliquin (Math. Program., 1992)

Generalized Hessian Properties of Regularized Nonsmooth Functions. - R. A. Poliquin; R. Tyrrell Rockafellar (SIAM J. Optim., 1996)

Tilt Stability of a Local Minimum. - R. A. Poliquin; R. Tyrrell Rockafellar (SIAM J. Optim., 1998)

Stability of Locally Optimal Solutions. - Adam B. Levy; R. A. Poliquin; R. Tyrrell Rockafellar (SIAM J. Optim., 2000)