Kurt and Barbara Aland, The Text of the New Testament, transl. E. Rhodes [Grand Rapids: Eerdmans, 1987], 48 (yes, the first ed.; my 2d ed. is at the seminary) says that there are explicit references to a four-Gospel collection (τετραευαγγέλιον) in Irenaeus by AD 180. But Aland does not give the reference in Irenaeus and it does not appear in a TLG search. Does anyone happen know where Irenaeus makes such a reference?