@article{oai:repository.dl.itc.u-tokyo.ac.jp:00000390,
 author = {Tsukuda, Tameshige},
 journal = {Journal of physics of the earth},
 month = {},
 note = {application/pdf},
 pages = {377--395},
 title = {An approximate theory for elastic waves propagated through a heterogeneous medium and its applications},
 volume = {20},
 year = {1972}
}