Madore, Barry F.; Rigby, Jane; Freedman, Wendy L.; Persson, S. E.; Sturch, Laura; Mager, Violet (2009). "The Cepheid Period–Luminosity Relation (The Leavitt Law) at Mid-Infrared Wavelengths. III. Cepheids in NGC 6822". The Astrophysical Journal. 693 (1): 936–939. arXiv:0812.0186. Bibcode:2009ApJ...693..936M. doi:10.1088/0004-637X/693/1/936. S2CID6028335.
"1912: Henrietta Leavitt Discovers the Distance Key." Everyday Cosmology. N.p., n.d. Web. October 20, 2014. "1912: Henrietta Leavitt Discovers the Distance Key". Everyday Cosmology. Archived from the original on November 11, 2020. Retrieved January 1, 2020.
Madore, Barry F.; Rigby, Jane; Freedman, Wendy L.; Persson, S. E.; Sturch, Laura; Mager, Violet (2009). "The Cepheid Period–Luminosity Relation (The Leavitt Law) at Mid-Infrared Wavelengths. III. Cepheids in NGC 6822". The Astrophysical Journal. 693 (1): 936–939. arXiv:0812.0186. Bibcode:2009ApJ...693..936M. doi:10.1088/0004-637X/693/1/936. S2CID6028335.
Madore, Barry F.; Rigby, Jane; Freedman, Wendy L.; Persson, S. E.; Sturch, Laura; Mager, Violet (2009). "The Cepheid Period–Luminosity Relation (The Leavitt Law) at Mid-Infrared Wavelengths. III. Cepheids in NGC 6822". The Astrophysical Journal. 693 (1): 936–939. arXiv:0812.0186. Bibcode:2009ApJ...693..936M. doi:10.1088/0004-637X/693/1/936. S2CID6028335.
Madore, Barry F.; Rigby, Jane; Freedman, Wendy L.; Persson, S. E.; Sturch, Laura; Mager, Violet (2009). "The Cepheid Period–Luminosity Relation (The Leavitt Law) at Mid-Infrared Wavelengths. III. Cepheids in NGC 6822". The Astrophysical Journal. 693 (1): 936–939. arXiv:0812.0186. Bibcode:2009ApJ...693..936M. doi:10.1088/0004-637X/693/1/936. S2CID6028335.
"1912: Henrietta Leavitt Discovers the Distance Key." Everyday Cosmology. N.p., n.d. Web. October 20, 2014. "1912: Henrietta Leavitt Discovers the Distance Key". Everyday Cosmology. Archived from the original on November 11, 2020. Retrieved January 1, 2020.