1. Annals of the Astrophysical Observatory of the Smithsonian Institution, vols. II to VII, 1908-1954 (see especially vol. III, pages 99 and 113 and vol. VII, page 176). Authors C. G. ABBOT, F. E. FOWLE, L. B. ALDRICH, W. H. HOOVER.
2. ANGSTROM, A., 1961, Absorption of solar radiation by atmospheric water vapor. Arkiv Geofys. 8.
3. ANGSTROM, A., 1964b, On the absorption of solar radiation by atmospheric water vapor. Arkiv Geofys. 4.