Alternative problems : An historical perspective -- Coincidence degree for perturbations of Fredholm mappings -- A generalized continuation theorem and existence theorems for Lx = Nx -- Two-point boundary value problems : Nonlinearities without special structure -- Approximation of solutions — The projection method -- Quasibounded perturbations of Fredholm mappings -- Boundary-value problems for some semilinear elliptic partial differential equations -- Periodic solutions of ordinary differential equations with quasibounded nonlinearities and of functional differential equations -- Coincidence index, multiplicity and bifurcation theory -- Coincidence degree for k-set contractive perturbations of linear Fredholm mappings -- Nonlinear perturbations of fredholm mappings of nonzero index.