(en) Jorge Melénde & Iván Ramírez, HIP 56948: A Solar Twin with a Low Lithium Abundance, The Astrophysical Journal Letters, 669, L89–L92 (2007), arXiv:0709.4290 (astro-ph) Voir en ligne.
(en) J. C. Hall & G. W. Lockwood, The Sun-Like Activity of the Solar Twin 18 Scorpii, The Astronomical Journal, 133, 2206–2008 (2007) astro-ph/0703450 Voir en ligne.