How to find staticmeshes which are using a certain materialInstances

Sorry for using such a confusing title,I just dont know how to explain it in short.

Here’s the thing:
I’m trying to build a BP that can loop though a folder to find all material Instances , and print there properties out to the log.
But i find out that a lot of material Instances are not being used by any static meshes , So i want to filter them out when printing out properties.Then i tried to get all the references to this material instance , but it seems there is not such node called “get all reference object” . The only thing close to what i want is"Find Soft Reference to Objects" , which does not work in my cause.
Turn out i may need a node “Find Hard Reference to Object” .

At end of the day , I just want to know whether a material Instance is used or not , And filter Not used ones IN Blueprint.