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3. A. M. Polyakov, “Quantum geometry of bosonic strings,” Phys. Lett. B, 103, 207–210 (1981).
4. L. D. Faddeev and L. A. Takhtajan, “Liouville model on the lattice,” in: Field Theory, Quantum Gravity, and Strings (Lect. Notes Phys., Vol. 246, H. J. de Vega and N. Sánchez, eds.), Springer, Berlin (1986), pp. 166–179.
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