This paper gives a method for determining the size of the first part of a two-stage sample for estimating the population mean with a given accuracy. The method is based on a scheme of Stein . The tables necessary for application of this method have been given. A more detailed summary will be found at the end of the Introduction.
B. M. Seelbinder. "On Stein's Two-stage Sampling Scheme." Ann. Math. Statist. 24 (4) 640 - 649, December, 1953. https://doi.org/10.1214/aoms/1177728919