There are a couple of ways.
1) Send the content creators a private message via the forums.
If this fails:
2) Right click on one of the assets and choose Open... then Edit Config File text.
The content-creator's email address and sometimes their website is located in there.
Once you've gotten the information you need, close the config file and in Content Manager right click and choose Revert to original.
Repeat for the other asset.