@article{MET_1985__32_176009,
     author = {B.F. Arnold},
     title = {Approximately {Optimum} {Two-Stage} {Sampling} {Plans.}},
     journal = {Metrika},
     pages = {293--314},
     year = {1985},
     volume = {32},
     zbl = {0586.62170},
     url = {http://geodesic.mathdoc.fr/item/MET_1985__32_176009/}
}