@article{oai:repository.dl.itc.u-tokyo.ac.jp:00041072,
 author = {Ushijima, Teruo},
 journal = {Scientific papers of the College of General Education, University of Tokyo},
 month = {},
 note = {application/pdf},
 pages = {27--42},
 title = {Spectral Theory of the Perturbed Homogeneous Elliptic Operator with Real Constant Coefficients},
 volume = {16},
 year = {1966}
}