How to find unreferenced blocks

Hi guys,

How can I ask Siyuan for unreferenced blocks? For example, because the document to which the link points has been deleted? Is there a snippet for SQL or something like that?

Sometimes i see a message on the right side that says that block xyz123 is deleted. But how do i find that references that point to dead blocks? I wanna fix them so i need to find them.

Thanks in advance

Achim