@article {chen2007asymptotic,
	title = {Asymptotic normality under two-phase sampling designs},
	journal = {Statistica Sinica},
	volume = {17},
	number = {3},
	year = {2007},
	pages = {1047},
	publisher = {C/O DR HC HO, INST STATISTICAL SCIENCE, ACADEMIA SINICA, TAIPEI 115, TAIWAN},
	author = {Chen, Jiahua and Rao, JNK}
}
