The Webis Bias Flipper 2018 (Webis-Bias-Flipper-2018) comprises 2781 events from allsides.com as of June 1st, 2012 till February 10, 2018. For each event, the title, the summary, all news portals belonging to the event, and the links to the news portals with respective bias were recorded. After that, we crawled the news portals with the given links to retrieve their headlines and the content of all articles, because the content is not provided on allsides.com. For each event we collected the corresponding news articles. A total of 6458 news articles are collected.

{"references": ["Wei-Fan Chen, Henning Wachsmuth, Khalid Al-Khatib, and Benno Stein. Learning to Flip the Bias of News Headlines. In 11th International Natural Language Generation Conference (INLG 2018), pages 79-88, November 2018. Association for Computational Linguistics"]}