Liferea dark panel icons

I found some really good monochrome panel icons for Liferea a while ago, but after a recent reinstall, I couldn't remember where, so I made some of my own.

If anybody recognises the icons, please let me know where I found them originally, so I can give credit to the designer.

Meanwhile, here are my icons for anybody who want to use them, and for me if I lose them again.

(Panel icons are elementary-xfce-dark).

Edit: Copy the icons to /usr/share/liferea/pixamps.