@article{oai:tsukuba.repo.nii.ac.jp:00017330,
 author = {Yoshiji, Katsuhiro},
 issue = {3},
 journal = {Tsukuba Journal of Mathematics},
 month = {Dec},
 pages = {741--746},
 title = {On the first eigenvalue of non-orientable closed surfaces},
 volume = {22},
 year = {1998}
}