Schroedinger upper bounds to semirelativistic eigenvalues
  Problems posed by semirelativistic Hamiltonians of the form   H = sqrt{m^2+p^2} + V(r) are studied. It is shown that energy upper bounds can be constructed in terms of certain related Schroedinger operators; these bounds include free parameters which can be chosen optimally. 
Richard L. Hall, Wolfgang Lucha