Name	Info	Provider	Link
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/31777741/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/31777741
	free resource	Korean Society of Obstetrics and Gynecology	https://ogscience.org/DOIx.php?id=10.5468/ogs.2019.62.6.445
	free resource	M2PI	https://dx.doi.org/10.5468/ogs.2019.62.6.445