@article{oai:tsukuba.repo.nii.ac.jp:00048834,
 author = {MELOTTI, Claudio},
 issue = {1},
 journal = {Tsukuba Journal of Mathematics},
 month = {Jul},
 pages = {121--152},
 title = {Double points of the slowness surface of the system of crystal acoustics for tetragonal crystals},
 volume = {37},
 year = {2013}
}