Schmidt, Karl Michael. "Dense point spectrum and absolutely continuous spectrum in spherically symmetric Dirac operators" Forum Mathematicum, 7.7 (2009): 459-476. Retrieved 19 Jun. 2013, from doi:10.1515/form.1995.7.459

Schmidt, K. (2009). Dense point spectrum and absolutely continuous spectrum in spherically symmetric Dirac operators. Forum Mathematicum, 7(7), pp. 1-779. Retrieved 19 Jun. 2013, from doi:10.1515/form.1995.7.459

Schmidt, Karl Michael. 2009. Dense point spectrum and absolutely continuous spectrum in spherically symmetric Dirac operators. Forum Mathematicum. 7(7): 1-779. Retrieved 19 Jun. 2013, from doi:10.1515/form.1995.7.459