Beat structure in the solution of scattering problems with nondecaying sources Marcelo J. Ambrosio, Lorenzo U. Ancarani, Antonio I. Gómez, Gustavo Gasaneo and Darío M. Mitnik Eur. Phys. J. D, 71 3 (2017) 54 Published online: 07 March 2017 DOI: 10.1140/epjd/e2017-70542-y