Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) Otuka Tetsuro and Seya Koichiro,High power aerial ultrasound source with stepped circular vibrating plate,THE JOURNAL OF THE ACOUSTICAL SOCIETY OF JAPAN,03694232,Acoustical Society of Japan,1991,47,7,478-483,https://cir.nii.ac.jp/crid/1390282681544242304,https://doi.org/10.20697/jasj.47.7_478