@article{WambsganssBrunnerSchindleretal.1999,
  author    = {Joachim Wambsganß and H. Brunner and Sabine Schindler and E. Falco},
  title     = {The gravitationally lensed quasar Q2237+0305 in X-rays: ROSAT/HRI detection of the "Einstein Cross"},
  year      = {1999},
}