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.