@article{shibaoka_1964, 
  title={Relation of Geological Condition and Character of Coal in the Yilutari District, Ishikari Coal Field}, 
  volume={43}, 
  DOI={10.3775/jie.43.6_494}, 
  publisher={The Japan Institute of Energy}, 
  author={Shibaoka}, 
  year={1964}
  }