Audi, Robert, Ed., The Cambridge Dictionary of Philosophy. Cambridge, England: Cambridge University Press, 1997.
Halperin, David M. One Hundred Years of Homosexuality: And Other Essays on Greek Love. New York: Routledge, 1990.
Plato, The Symposium. Translated by Christopher Gill. Harmondsworth: Penguin Books, 1999.
Plato, Complete Works. Edited by John M. Cooper. Indianapolis, Indiana: Hackett Publishing Company, 1997.
You do not have to look outside you as everything is in your "self", everybody is the two energies (woman-man/yin-yang/...) and if you awaken your "opposite" you are "one", you are realized, totally happy. This is called e.g. in the Bible the Holy or Mystic Marriage. Also the alchemists describe it as "Coniunctio Oppositorum", the Philosopher's Stone, make Gold from Lead,... See the writings of the Mystics too. Etc.