@article{oai:bunkyo.repo.nii.ac.jp:00005750,
 author = {Negami, Seiya},
 journal = {情報研究, Information and Communication Studies},
 month = {2000-01-01, 2011-02-23},
 note = {We shall show that a connected graph G0 is projective-planar if and only if it has a series of double coverings Gn → Gn-1 → … → G0 with Gn planar, called a planar tower, and that a connected graph is projective-planar if and only if it has a projective-planar double covering. This works as an evidence supporting Negami's planar cover conjecture., 情報学シンポジウム特集号\nタイトル日本語表記 : グラフの平面的被覆の搭載成法\n著者名日本語表記 : 根上, 生也},
 pages = {25--29},
 title = {Tower Construction of Planar Coverings of Graphs},
 volume = {25},
 year = {}
}