5OFER G. Returns to Scale in Retail Trade[J]. Re- view of Income and Wealth, 1973 (19) : 363-384.
6MESSINGER P R, NARASIMHAN C.Model of Retail Formats Based Shopping On Consumers" Economizing On Time[J].Marketing Science, 1997 (1) 1-23.
7RATCHFORD B T, BROWN J R.A Study of Produc- tivity Changes in Food Retailing [J].Marketing Science, 1985 (4) : 292-311.
8TILLEY P R, HICKS R.Economies of Scale in Super- markets[J].Journal of Industrial Economics, 1970 (1) : 1-5.
9KEH H T, CHU S.Retail Productivity and Scale E- conomies at the Firm Level: A DEA Approach[J].Omega, 2003 (31) :75-82.
10BARROS C P, ALVES C.An Empirical Analysis of Productivity Growth in a Portuguese Retail Chain Using Malmquist Productivity Index[J].Joumal of Retailing and Con- sumer Services, 2004 (11) : 269-278.