1. D. Friedan and S.H. Shenker, The analytic geometry of conformal field theory, EFI preprint 86-18A.
2. Dual theory,1974
3. Superstrings, the first fifteen years,1985
4. Proc. Workshop on Unified string theories,1986
5. Conformal invariance, supersymmetry, and string theory;Friedan;Nucl. Phys. B,1985