@article{SchmidtWambsganssPenetal.2001,
  author    = {Schmidt, Robert W. and Wambsganß, Joachim and Pen, U.-L. and Turner, E. L.},
  title     = {APO monitoring of Q2237+0305 in 1995-97 : evidence for microlensing},
  isbn      = {1-583-81074-9},
  year      = {2001},
  language  = {en}
}