@article {logan2010density,
	title = {Density of rational points on diagonal quartic surfaces},
	journal = {Algebra \& Number Theory},
	volume = {4},
	number = {1},
	year = {2010},
	pages = {1{\textendash}20},
	publisher = {Mathematical Sciences Publishers},
	author = {Logan, Adam and McKinnon, David and van Luijk, Ronald}
}