Long-term optical spectroscopic variations in blazar 3C 454.3Krzysztof Nalewajko, Alok C. Gupta, Mai Liao, Krzysztof Hryniewicz, Maitrayee Gupta and Minfeng GuA&A, 631 (2019) A4DOI: https://doi.org/10.1051/0004-6361/201935904
