Correlation between activity indicators: Hα and Ca II lines in M-dwarf stars R. V. Ibañez Bustos, A. P. Buccino, M. Flores, C. F. Martinez and P. J. D. Mauas A&A, 672 (2023) A37 Published online: 27 March 2023 DOI: 10.1051/0004-6361/202245352