@article{1309755,
  author = {D. Psaltis and T. Johannsen},
  title = {A Ray-tracing Algorithm for Spinning Compact Object Spacetimes with Arbitrary Quadrupole Moments. I. Quasi-Kerr Black Holes},
  year = {2012},
  journal = {ApJ},
  volume = {745},
  pages = {1},
  language = {eng},
}