1. G. Bonelli and M. Matone, hep-th 9602174, Phys. Rev. Lett., 76 (1996), 4107–4110
2. R. Carroll, hep-th 9607219,9610216,9702138,9705229; Nucl. Phys. B, 502 (1997), to appear
3. R. Carroll, Topics in soliton theory, North-Holland, 1991
4. R. Carroll, Applicable Analysis, 49 (1993), 1-31; 56 (1995), 147–164
5. R. Carroll, solv-int 9606005, Proc. Second World Congress Nonlinear An-alysts, North-Holland, to appear