1. On the brightness of the sky and total amount of starlight;Yntema;Publ. Astr. Groningen,1909
2. “Recherches sur le Spectre Solaire,”;ÅNGSTRÖM,1868
3. On the general auroral illumination of the sky and the wavelength of the chief aurora line;Slipher;Astrophys. J.,1919
4. Absolute intensity of the aurora line in the night sky and the number of atomic transitions;Rayleigh;Proc. Roy. Soc. (London),1930
5. “Physics of the Aurora and Airglow,”;Chamberlain,1961