Herbert Weir Smyth, A Greek Grammar for Colleges

a. In the nominative case, when standing alone: αὐτοὶ τὴν γῆν ἔσχον they (the Athenians) seized the land themselves T. 1.114. Here αὐτός emphasizes the word understood and is not a personal pronoun.

b. In any case, when in the predicate position (1168) with a substantive, or in agreement with a pronoun: αὐτὸς ὁ ἀνήρ, ὁ ἀνὴρ αὐτός the man himself, αὐτοῦ τοῦ ἀνδρός, τοῦ ἀνδρὸς αὐτοῦ, etc.