Analysis of information sources in references of the Wikipedia article "Tetragrammaton" in English language version.
ἀτὰρ καὶ τὸ τετράγραμμον ὄνομα τὸ μυστικόν, ὃ περιέκειντο οἷς μόνοις τὸ ἄδυτον βάσιμον ἦν· λέγεται δὲ Ἰαοὺ [also ἰαοῦε; ἰὰ οὐὲ]
...pronouncing the God of Israel's proper name," known as the holy or divine tetragrammaton, written with four consonants, YHWH, in the Hebrew alphabet. In order to vocalize it, it is necessary to introduce vowels that alter the written and spoken forms of the name (i.e. "Yahweh" or "Jehovah").