[en] Lattice gauge calculations have shown that the interaction between quarks is described by a Linear potential at large distances. Quarks in hadrons are only properly described by two-body relativistic bound state equations [1,2] which are most easily solved in momentum space. However the Linear potential leads to singularities in momentum space [3]. We show how to obtain exact solution the Schrodinger equation using a subtraction procedure to handle the singularities. This is generalized to a relativistic kernel by replacing 3-vectors with 4-vectors. We solve six different 3-dimensional reductions of the Bethe-Salpeter equation (BSE) by using a subtraction procedure tailored to the relativistic kernels