@article {13441,
	title = {Clarifying Some Aspects of Variance Estimation in Two-Phase Sampling},
	journal = {Journal of Survey Statistics and Methodology},
	volume = {3},
	year = {2015},
	pages = {524{\textendash}542},
	author = {J-F Beaumont and Audrey B{\'e}liveau and David Haziza}
}