Are you questioning the source of a specific piece of data you interpret to be anti-union or you questioning what is the source of peoples opinion on why they a

Are you questioning the source of a specific piece of data you interpret to be anti-union or you questioning what is the source of peoples opinion on why they are anti union. If you are questioning the source of a specific piece of data than be clear about what that data is. If you are asking people to cite a source for a general opinion they personally hold, they don't owe you that.