  Considered is the formulation for the superstring action in 6 and 10
dimensions involving supertwistor variables that appropriately generalize
4-dimensional Ferber supertwistors. Equations of motion and kappa-symmetry
transformations in terms of the supertwistors are derived. It is shown that
covariant kappa-symmetry gauge fixing reduces superstring action to the
quadratic one with respect to supertwistors. Upon gauge fixing remaining
symmetries it can be cast into the form of the light-cone gauge Green-Schwarz
superstring action.
