  We prove existence and uniqueness of solutions of a large class of
initial-boundary-value problems characterized by a quasi-linear third order
equation (the third order term being dissipative) on a finite space interval
with Dirichlet, Neumann or pseudoperiodic boundary conditions. The class
includes equations arising in superconductor theory, such as a well-known
modified sine-Gordon equation describing the Josephson effect, and in the
theory of viscoelastic materials.
