Urbanus, W. H., Wojke, R. G. C., Steenvoorden, R. ., Bannenberg, J. G., Klein, H. ., Schempp, A. ., … van Amersfoort, P. W. (1989). Simultaneous Transport of N+ and N-2+ Ions through a Periodic Focusing Quadrupole Channel. Nuclear Instruments & Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipment, 276, 433-444. https://doi.org/10.1016/0168-9002(89)90568-8 (Original work published)
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