@article{oai:tsukuba.repo.nii.ac.jp:00016149,
 author = {Takahashi, Moto-o},
 issue = {1},
 journal = {Tsukuba Journal of Mathematics},
 month = {Jun},
 pages = {175--189},
 title = {On the presentations of the fundamental groups of 3-manifolds},
 volume = {13},
 year = {1989}
}