@article{campbell_moore_1917, 
  title={Spectrographic Observations of Rotation in the Planetary Nebula N. G. C. 7026}, 
  volume={29}, 
  number={167}, 
  publisher={The Astronomical Society of the Pacific}, 
  author={Campbell, W. W. and Moore, J. H.}, 
  year={1917}, 
  month={Feb}
  }