Variations in the thermodynamic state of the chromosphere over the sunspot cycleDOI: info:10.5479/si.00810231.2-4.35v. 2No. 4Smithsonian Institution35-50
Athay, R. Grant, Menzel, Donald Howard, and Orrall, Frank Quimby. 1957. "Variations in the thermodynamic state of the chromosphere over the sunspot cycle." Smithsonian Contributions to Astrophysics, 2, (4) 35–50. https://doi.org/10.5479/si.00810231.2-4.35.