Are the Gospel Authors in Early Antiquity Quoting Matthew and Mark?

It gets tricky early on in the early second century. There are church fathers who appear to be quoting Matthew and Luke, but they don't call them Matthew and Luke. And so it's not quite clear. By the end of the second century, Irenaeus, who's a bishop of an important church in Gaul, modern France in Lyon, he quotes Matthew, Mark, Luke and John. He actually quotes those books. So we know that by then, and the way he talks about them, it's clear they're really widely known by this time.