Target space duality in string theory

This paper is devoted to recent progress made towards the understanding of closed bosonic and fermionic string perturbation theory, formulated in a Lorentz-covariant way on Euclidean space-time. Special emphasis is put on the fundamental role of Riemann surfaces and supersurfaces. The differential and complex geometry of their moduli space is developed as needed. New results for the superstring presented here include the supergeometric construction of amplitudes, their chiral and superholomorphic splitting and a global formulation of supermoduli space and amplitudes.

The Geometry of String Perturbation Theory

http://cds.cern.ch/record/241379/files/arXiv:hep-th_9210010.pdf

W symmetry in conformal field theory

Space-time supersymmetry in compactified string theory and superconformal models

These lectures consisted of an elementary introduction to conformal field theory, with some applications to statistical mechanical systems, and fewer to string theory. 
Contents: 
1. Conformal theories in d dimensions 
2. Conformal theories in 2 dimensions 
3. The central charge and the Virasoro algebra 
4. Kac determinant and unitarity 
5. Identication of m = 3 with the critical Ising model 
6. Free bosons and fermions 
7. Free fermions on a torus 
8. Free bosons on a torus 
9. Affine Kac-Moody algebras and coset constructions 
10. Advanced applications

/pdf/applied-conformal-field-theory-b0qg8e4ols.pdf

Applied Conformal Field Theory

https://cds.cern.ch/record/438898/files/197512047.pdf

R. Musto

Papers

Supersymmetric Strings and Color Confinement

Dual String with U(1) Color Symmetry

Dual string models with nonabelian color and flavor symmetries.