The mythic tradition of dle Greeks is protean. Each of the vast number of stories is itself variable, appearing now in one form, now in another, often standing alongside other versions which it flatly contradicts. Critical study of this remarkable tradition is doubly vexed, firSt by received myth's intrinsically fluid nature, then by the fragmentary preservation of mythic source material.
McDermott, Emily A. "Double Meaning and Mythic Novelty in Euripides' Plays," Transactions of the American Philological Association, Vol. 121 (1991). http://scholarworks.umb.edu/classics_faculty_pubs/11
Transactions of the American Philological Association