I've known that you can't use a specific time expression with present perfect tense.
However, I've seen a sentence like: We've established, a long time ago, that this is Canadian property.
The publisher of the book with the sentence is thought to be one of the most authoritative ones in my country,
so I thought "Am I wrong? Did I misunderstand the grammatical point?"
I also thought that it could be correctly used when it comes to be among two commas.
So, here is the thing that I want to know:
Can I use specific time expressions like ago, when, or yesterday with present perfect tense?