@conference {crow1977shadow,
	title = {Shadow algorithms for computer graphics},
	booktitle = {Acm siggraph computer graphics},
	volume = {11},
	number = {2},
	year = {1977},
	pages = {242{\textendash}248},
	publisher = {ACM},
	organization = {ACM},
	author = {Crow, Franklin C}
}
