New strings with world-sheet supersymmetry
  We suggest a new model of string theory with world-sheet supersymmetry. It possesses an additional global fermionic symmetry which is similar in many ways to BRST symmetry. The spectrum consists of massless states of Rarita-Schwinger fields describing infinite tower of half-integer spins. 
A.Nichols, R.Manvelyan and G.Savvidy