Col Reference --- --------- R1 Lindoff U. 1968, Ark. Astr. 4, 471 R2 Bica E., et al. 2006, Astron. Astrophys. 460, 83 Back to the form
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R1 Lindoff U. 1968, Ark. Astr. 4, 471
R2 Bica E., et al. 2006, Astron. Astrophys. 460, 83