We study string theory in the background of a two-dimensional black hole
which is described by an SL(2,R)/U(1) coset conformal field theory. We
determine the spectrum of this conformal field theory using supersymmetric
quantum mechanics and give an explicit form of the vertex operators in terms of
the Jacobi functions. We also discuss the applicability of SUSY quantum
mechanics techniques to non-linear σ-models.Comment: 21 page