Butler, Judith. The Psychic Life of Power. Stanford: Stanford UP, 1997.
… gender is performative, by which I meant that no gender is “expressed” by actions, gestures, or speech, but that the performance of gender produces retroactively the illusion that there is an inner gender core. That is, the performance of gender retroactively produces the effect of some true or abiding feminine essence or disposition, so that one cannot use an expressive model for thinking about gender. Moreover, I argued that gender is produced as a ritualized repetition of conventions, and that this ritual is socially compelled in part by the force of a compulsory heterosexuality. 144