Improve usability of 'Sources'

The Problem: Working with sources is frustrating—I can only see 4 at once, can't tell which ones I've clicked, and keep losing track of what I've already read.

Ideas to Fix:

• Show sources as cards,

• Show all when expanded (not just 4),

• If no. of sources is bigger than default, add "View All" button,

• Change color of clicked links so I know what I've read,

• Add "Open All" or "Copy Links" buttons for quick access,

• Maybe try a sidebar for sources—would make research much easier!,