Investigating the reasons of variability in Si IV and C IV broad absorption line troughs of quasarsDimitrios Stathopoulos, Evangelia Lyratzi, Emmanuel Danezis, Antonios Antoniou and Dimitrios TzimeasEur. Phys. J. D, 71 9 (2017) 224DOI: https://doi.org/10.1140/epjd/e2017-70749-x