doi.org/10.1088/0950-7671/44/2/306
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Schutten, J., van Deenen, P. J., de Haas, E., & de Heer, F. J. (1967). A semi-automatic monochromator for the determination of excitation cross sections. J. Sci. Instrum., 44, 153–155. doi:10.1088/0950-7671/44/2/306