Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) Kazuhiko Imano and H. Inoue and K. Takasaki,On-axis ultrasonic field characteristics of monopole pulse radiated from planar and concave transducers,1998 IEEE Ultrasonics Symposium. Proceedings (Cat. No. 98CH36102),,IEEE,2002-11-27,2,,1039-1042,https://cir.nii.ac.jp/crid/1874242817948035456,https://doi.org/10.1109/ultsym.1998.764983