Getting the BlockRefrence list

hi, Is there anyway to get the list of InstanceDefinitions and use it to grasshopper?

I've tried use " "Rhino.DocObjects.Tables." but it always give this message:

"0. Error (CS0143): The type 'Rhino.DocObjects.Tables.InstanceDefinitionTable' has no constructors defined (line 71)"

Does anybody have a solution ??