found clue to Krebiozen identity shortly after starting work on 20,000 spectrographs. St. Louis Post-Dispatch. 1963-09-08: 24 [2017-05-07]. (原始内容存档于2018-06-12)
开放目录项目中的“光波分光計” Spectrograph for astronomical Spectra Photographs of spectrographs used in the Lick Observatory from the Lick Observatory Records Digital