1. Romer Christina D. 1986 New Estimates of Prewar Gross National Product and Unemployment. Journal 46, no. 2 341–52.
2. Leung Siu Fai , and Shihti Yu. 1996 On the Choice between Sample Selection and Two-Part Models. Journal of Econometrics 72,no. 1–2 197–229.
3. Rosenbloom Joshua L. 2002 Looking for Work, Searching for Workers: American Labor Markets during Industrialization. New York: Cambridge University Press
4. Friedman Milton. 1968 The Role of Monetary Policy. American Economic Review 58,no. 1 1–15.
5. Atack Jeremy , Fred Bateman , and Robert Margo. 2002 Part-Year Operation in Nineteenth-Century American Manufacturing: Evidence from the 1870 and 1880 Censuses. This Journal 62, no. 3 792–809.