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(en) Jenna Ryon, Matthew D. Shetrone et Graeme H. Smith, « Comparing the CaiiH and K Emission Lines in Red Giant Stars », Publications of the Astronomical Society of the Pacific, vol. 121, no 882, , p. 842 (DOI10.1086/605456, Bibcode2009PASP..121..842R, arXiv0907.3346, S2CID17821279)
(en) Jenna Ryon, Matthew D. Shetrone et Graeme H. Smith, « Comparing the CaiiH and K Emission Lines in Red Giant Stars », Publications of the Astronomical Society of the Pacific, vol. 121, no 882, , p. 842 (DOI10.1086/605456, Bibcode2009PASP..121..842R, arXiv0907.3346, S2CID17821279)