  Construction of integrable field theories in space with a boundary is
extended to fermionic models. We obtain general forms of boundary interactions
consistent with integrability of the massive Thirring model and study the
duality equivalence of the MT model and the sine-Gordon model with boundary
terms. We find a variety of integrable boundary interactions in the $O(3)$
Gross-Neveu model from the boundary supersymmetric sine-Gordon theory by using
boson-fermion duality.
