Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) K. W. Ehlers and K. N. Leung,Multicusp negative ion source,Review of Scientific Instruments,0034-6748,AIP Publishing,1980-06-01,51,6,721-727,https://cir.nii.ac.jp/crid/1364233270043724672,https://doi.org/10.1063/1.1136302