Uncertainty in Measurements of the Distances of Scattering Screens in
  Pulsar Observations
  In our previous paper (Popov et al. (2016)) we investigated properties of the
ionized interstellar medium in the direction of three distant pulsars:
B1641-45, B1749-28, and B1933+16. We found that uniformly distributed
scattering material cannot explain measured temporal and angular broadening. We
applied a model for a thin scattering screen and found the distances to the
scattering screens in all directions. In this paper we consider more
complicated models of scattering material distribution, such as models
containing both uniformly distributed medium and thin screen. Based on these
models we estimate the accuracy of localisation of scattering screens and
possible relative contribution of each scattering component.
