The charged dust solution of Ruban -- matching to Reissner--Nordstr\"om
  and shell crossings
  The maximally extended Reissner--Nordstr\"om (RN) manifold with $e^2 < m^2$
begs for attaching a material source to it that would preserve the infinite
chain of asymptotically flat regions and evolve through the wormhole between
the RN singularities. So far, the attempts were discouraging. Here we try one
more possible source -- a solution found by Ruban in 1972 that is a charged
generalisation of an inhomogeneous Kantowski--Sachs-type dust solution. It can
be matched to the RN solution, and the matching surface must stay all the time
between the two RN event horizons. However, shell crossings do not allow even
half a cycle of oscillation between the maximal and the minimal size.
