I've had the icons for something like 3 years. I can't remember where I found them, nor can I find the www. with the originals.
If you want to use the icons then please feel free to download the zip folder from the link at the bottom. Though bear in mind that it's not a complete set. And they didn't all come from the same place - I think the lt.png and nook.png came from Deviant art. Also, I tweaked the connect-share-on icon so that it glows red when the calibre server is broadcasting.
One last thing, the link is to Dropbox and it will expire in a week. So best get your skates on.
https://www.dropbox.com/s/3t9pigmhyp...icons.zip?dl=0