@Article{BR99b,
  author = 	 {Wolfgang Bangerth and Rolf Rannacher},
  title = 	 {Finite element approximation of the acoustic wave equation: {E}rror
                  control and mesh adaptation},
  journal = 	 {East--West J. Numer. Math.},
  year = 	 1999,
  volume =	 7,
  number = 	 4,
  pages =	 {263--282}
}