@article{oai:nipr.repo.nii.ac.jp:00002247,
 author = {Hansen, S.},
 journal = {Memoirs of National Institute of Polar Research. Special issue},
 month = {Mar},
 note = {P(論文)},
 pages = {403--404},
 title = {Report 4. Methods of maintaining a vertical borehole},
 volume = {49},
 year = {1994}
}