Biblio

Y. - R. Li, Wang, J. - M., Zhang, Z. - X., Wang, K., Huang, Y. - K., Lu, K. - X., Hu, C., Du, P., Bon, E., Ho, L. C., Bai, J. - M., Bian, W. - H., Yuan, Y. - F., Winkler, H., Denissyuk, E. K., Valiullin, R. R., Bon, N., and Popović, L. Č., “A Possible \ensuremath\sim}20 yr Periodicity in Long-term Optical Photometric and Spectral Variations of the Nearby Radio-quiet Active Galactic Nucleus Ark 120}”, \apjs, vol. 241, p. 33, 2019.