@article{oai:nagoya.repo.nii.ac.jp:00020268,
 author = {KAMADA, Tetsuo and TOKUDA, Susumu and HIRONAGA, Tokie},
 journal = {Proceedings of the Research Institute of Atmospherics, Nagoya University},
 month = {Mar},
 note = {January 1981 marked the passing of a decade since we began phase measurement of VLF standard signals. During this decade, there was a solar activity minimum year of 1976. This report describes some statistical results of sudden phase anomalies(SPAs) before and after 1976, at which remarkable differences in the occurrence of SPAs appeared according to the solar activity. That is, occurrence numbers of SPA for five years before 1976 were very few as compared with the one for five years after 1976. In order to elucidate the contribution of solar X-ray bursts to the increase of ionization in the D region, a typical example of a big SPA event observed at Toyokawa associated with a big solar X-ray burst is shown.},
 pages = {1--19},
 title = {ON SPA EVENTS OBSERVED AT TOYOKAWA DURING A DECADE FROM 1971},
 volume = {29},
 year = {1982}
}