@article{oai:repository.dl.itc.u-tokyo.ac.jp:00049251,
 author = {Nagase, Teruo and Shima, Akiko},
 issue = {2},
 journal = {Journal of Mathematical Sciences The University of Tokyo},
 month = {Mar},
 pages = {195--237},
 title = {Properties of Minimal Charts and Their Applications IV : Loops},
 volume = {24},
 year = {2017}
}