In this paper, Havelock argues that the distinction between "early" "middle" and "late" dialogues makes little sense. All of the dialogues are Plato's construction; there is no reason to accept any of them as intended to be accurate representations of the historical Socrates. The Apology, often taken as a faithful representation of the historical Socrates, is rather a genre piece, in the tradition of Gorgias' Palamedes. Compare Isocrates' Antidosis. Havelock takes the movement from the orality of Socrates to the literacy of Plato as critical movement in the Athenian thought.
Havelock, Eric A., "The Socratic Problem: Some Second Thoughts" (1979). The Society for Ancient Greek Philosophy Newsletter. 84.