@article {petkau1980frequentist,
	title = {Frequentist properties of three stopping rules for comparative clinical trials},
	journal = {Biometrika},
	volume = {67},
	number = {3},
	year = {1980},
	pages = {690{\textendash}692},
	publisher = {Biometrika Trust},
	author = {Petkau, A.John}
}
