@book{99111,
	author = {Basopo, Norah and NUST.},
	title = {Effects of pesticides on esterase activity of two species of freshwater snails helisoma duryi and lymnaea natalensis /},
	publisher = {Natioanl University of Science and Technology,},
	year = {2007},
	address = {Bulawayo :},
	note = {Includes bibliographical references.}
}