@article{oai:repository.dl.itc.u-tokyo.ac.jp:00037771,
 author = {Hirayama, S.},
 journal = {Journal of the College of Science, Imperial University of Tokyo},
 month = {Jun},
 note = {application/pdf},
 pages = {1--16},
 title = {The Systematic Motions of Sun-spots},
 volume = {32},
 year = {1912}
}