1. Minimal realizations and spectrum generating algebras
2. Singular unitary representations
3. B. Kostant,Operator Algebras, Unitary Representations, Enveloping Algebras, and Invariant Theory (Paris, 1989), Progress in Mathematics Vol. 42 (Birkhäuser Boston, Boston, MA, 1990), pp. 85–124.
4. Unitarization of a singular representation ofSO(p, q)
5. D. Kazhdan and G. Savin, Festschrift in Honor of I. I. Piatetski-Shapiro on the Occasion of His Sixtieth Birthday, Part I (Ramat Aviv, 1989), Israel Mathematics Conference Proceedings Vol. 2 (Weizmann, Jerusalem, 1990), pp. 209–223.