Professor Eduard Karl August Riehm in his Handwörterbuch des Biblischen Altertums für gebildete Bibelleser (G) Dictionary of biblical antiquity for educated readers of the Bible (1884) p. 1620, puts
Acts 2:38, 8:16, 10:48, 19:5 and
Romans 6:3 as the real mode of baptism and dismisses
Matthew 28:19 as not authentic.