Wolf P, Alonso R, Blas D. Searching for ultra-light dark matter with atomic spectroscopy. In Auge E, Dumarchez J, Tran Thanh Van J, editors, Proceedings of the 54th Rencontres de Moriond - 2019 Gravitation. ARISF. 2019. p. 183-189. (Proceedings of the 54th Rencontres de Moriond - 2019 Gravitation).