Zhao, G.; Qiu, H. M.; Mao, Shude. High-Resolution Spectroscopic Observations of Hipparcos Red Clump Giants: Metallicity and Mass Determinations. The Astrophysical Journal. 2001, 551 (1): L85. Bibcode:2001ApJ...551L..85Z. doi:10.1086/319832.
Ayres, Thomas R.; Simon, Theodore; Stern, Robert A.; Drake, Stephen A.; Wood, Brian E.; Brown, Alexander. The Coronae of Moderate-Mass Giants in the Hertzsprung Gap and the Clump. The Astrophysical Journal. 1998, 496 (1): 428–448. Bibcode:1998ApJ...496..428A. doi:10.1086/305347.
Zhao, G.; Qiu, H. M.; Mao, Shude. High-Resolution Spectroscopic Observations of Hipparcos Red Clump Giants: Metallicity and Mass Determinations. The Astrophysical Journal. 2001, 551 (1): L85. Bibcode:2001ApJ...551L..85Z. doi:10.1086/319832.
Ayres, Thomas R.; Simon, Theodore; Stern, Robert A.; Drake, Stephen A.; Wood, Brian E.; Brown, Alexander. The Coronae of Moderate-Mass Giants in the Hertzsprung Gap and the Clump. The Astrophysical Journal. 1998, 496 (1): 428–448. Bibcode:1998ApJ...496..428A. doi:10.1086/305347.