@techreport{Tolbert1966,
author = {Tolbert, C.M. and Sizer, M.},
title= {U.S. Commuting Zones and Labor Market Areas: A 1990 Update},
year = {1966},
URL = {http://catalogue.nla.gov.au/Record/4130913},
publisher = {Economic Research Service, Rural Economy Division, U.S. Department of Agriculture},
address = {Washington, D.C.},
institution = {ERS Staff Paper Number 9614},
}