How to verify nonce from Bulk/Quick Edit in save_post?

Question

I need to do something specific in my save_post callback for bulk and/or quick edits, so how do I check the nonce for that? I can only find _wpnonce in the edit.php html source, but can't find an action to match it with. I also tried check_admin_referrer() (no arguments) but it fails.

1. What nonce whould I check for? OR

2. Should I check for something else in save_post to know it's being fired from a

   a. bulk edit or

   b. quick edit action? I read that DOING_AJAX is there for quick edit, but is that enough on its own? what about for bulk edit?