Altmetric started tracking attention to research across various attention sources in October 2011. The table below lists the dates when source coverage began and ended, if applicable. 

Coverage dates refer to when Altmetric set up tracking of each source. We may, however, hold historical data for certain sources. For example, in policy documents and citations we are often able to collect historical data.

Coverage ended means that we stopped collecting data on this date. All data previously aggregated will remain in our database where possible and continue to appear in Altmetric details pages, Explorer, and the Altmetric API.

For News sources, we redeveloped our news tracking system and significantly improved coverage in December 2015: articles published after this date will have a higher number of news stories associated with them.