This book deals with several bound state and scattering problems in quantum theory. There exist numerous unsolved bound state problems in both non- relativistic and relativistic theories. Solving them either analytically or numerically can be of immense importance both from theoretical as well as from experimental points of view. This is the task undertaken in this book. Several interesting bound state problems are solved exactly. Some problems are solved using well-established methods. Wherever possible, the results of our calculations are compared with those obtained by using different...