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.