AUTHOR=Kozłowski Szymon TITLE=Optical Variability of Active Galactic Nuclei JOURNAL=Frontiers in Astronomy and Space Sciences VOLUME=4 YEAR=2017 URL=https://www.frontiersin.org/articles/10.3389/fspas.2017.00014 DOI=10.3389/fspas.2017.00014 ISSN=2296-987X