1. Parts of the article are taken from the book: Busch U (Ed.). Wilhelm Conrad Röntgen – A shining life for science. Classic texts in science. Birkhäuser; 2021. p. 94–6.
2. More H. Cathode rays; 2020. https://thefactfactor.com/tag/faradays-dark-space/. Site visited 20.10.2022.
3. Hauksbee F. Physico-mechanical experiments on various subjects, containing an account of several surprizing phaenomena touching light and electricity. Producible on the attrition of bodies. With many other remarkable appearances, not before observ'd. Together with the explanations of all the machines, (the figures of which are curiously engrav'd on copper) and other apparatus us'd in making the experiments. London, Printed by R. Brugis, for the author; 1709. p. 133–97. https://archive.org/search.php?query=Hauksbee%20Physico-Mechanical
4. On the spectra of ignited gases and vapours with especial regard to the same elementary gaseous substance;Hittorf;Philos Trans R Soc (Lond),1865
5. Ueber die Elektricitätsleitung der Gase;Hittorf;Ann Phys Chem,1869