Chiral bosonic supercurrents and four-dimensional fermionic string models

World-sheet supercurrents represented in terms of chiral bosons are constructed and the resulting constraints on the spectrum, interaction couplings, and space-time supersymmetry of the string models generated by them are analyzed. Explicit examples of fermionic string models are described. A description of the cocycle operators in the supercurrent and in the interaction couplings is given. © 1989