@article{oai:tsukuba.repo.nii.ac.jp:00032859,
 author = {平良, 和昭 and TAIRA, Kazuaki},
 issue = {8},
 journal = {Proceedings of the Japan Academy},
 month = {},
 pages = {546--548},
 title = {Hypoelliptic Differential Operators with Double Characteristics},
 volume = {50},
 year = {1974},
 yomi = {タイラ, カズアキ}
}