@article {37189,
	title = {Have Individual Stocks Become More Volatile? An Empirical Exploration of Idiosyncratic Risk},
	journal = {Journal of Finance},
	volume = {56},
	number = {1},
	year = {2001},
	pages = {1-43},
	author = {John Y. Campbell and Martin Lettau and Burton Malkiel and Yexiao Xu}
}
