Não informado. (1939). Quarterly Bulletin on Solar Activity. International Astronomical Union.
Lua i Stíl Chicago (17ú heag.)Não informado. Quarterly Bulletin on Solar Activity. Zurich, Suíça: International Astronomical Union, 1939.
Lua MLA (8ú heag.)Não informado. Quarterly Bulletin on Solar Activity. International Astronomical Union, 1939.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.