@book{4099,
	author = {Roos, Willem Lodewyk. and Institute for Manpower Research (Human Sciences Research Council)},
	title = {'n Verkenningstudie ten opsigte van die probleem van onderprestasie op standerd ses-vlak /},
	publisher = {Instituut vir Mannekragnavorsing,},
	year = {1973.},
	address = {[Pretoria] :}
}