1. Exactly solvable field theories of closed strings
2. M. Douglas and S. Shenker, Strings in less than one dimension, Rutgers preprint RU-89-34.
3. D. Gross and A. Migdal, Nonperturbative two dimensional quantum gravity, Princeton preprint PUPT-1148.
4. The ising model coupled to 2D gravity. A nonperturbative analysis
5. V. Kazakov, The appearance of matter fields from quantum fluctuations of 2D gravity, Niels Bohr Institute preprint NBI-HE-89-25.