%%% bibliography comes here or something
\vfill\break
\begin{thebibliography}{van de Hulst}
\bibitem[van de Hulst]{hulst} H.~C. van~de~Hulst et al.,
      {\em The spiral structure of the outer part of the Galactic
      System derived from the hydrogen emission at 21~cm wavelength.}
      Bull. of the Astron. Institutes of the Netherlands, May 1954.
\bibitem[Shklovski]{folder} I.~S. Shklovski,
      {\em Cosmic Radio Waves.}
      Harvard University Press, Cambridge, Massachusetts, 1960.
\bibitem[Allen]{allen} C.~W.~Allen,
      {\em Astrophysical Quantities.}
      The Athelone Press, London, 1976.
\bibitem[Shu]{shu} Frank~H. Shu,
      {\em The Physical Universe: an introduction to astronomy.}
      University Science Books, Mill Valley, California, 1982.
\bibitem[Noyes]{sun} Robert~W. Noyes,
      {\em The Sun, our star.}
      Harvard University Press, Cambridge, Massachusetts, 1982.
\end{thebibliography}









