@book{2439,
	author = {World Health Organization},
	title = {WHO recommended surveillance standards},
	publisher = {WHO,},
	year = {1999.},
	address = {Geneva :},
	edition = {2nd edition},
	url = {https://apps.who.int/iris/bitstream/handle/10665/65517/WHO_CDS_CSR_ISR_99.2.pdf?sequence=1&isAllowed=y}
}