Molecular ion abundances in the diffuse ISM: CF+, HCO+, HOC+, and C3H+ M. Gerin, H. Liszt, D. Neufeld, B. Godard, P. Sonnentrucker, J. Pety and E. Roueff A&A, 622 (2019) A26 Published online: 24 January 2019 DOI: 10.1051/0004-6361/201833661