The physical meaning of the "boost-rotation symmetric" solutions within   the general interpretation of Einstein's theory of gravitation
  The answer to the question, what physical meaning should be attributed to the so-called boost-rotation symmetric exact solutions to the field equations of general relativity, is provided within the general interpretation scheme for the ``theories of relativity'', based on group theoretical arguments, and set forth by Erich Kretschmann already in the year 1917. 
S. Antoci, D.-E. Liebscher, L. Mihich