求助两篇外文文献，感激不尽~~~

Putman, S.H., and Chung, S.H., 1989. Effects of spatial systems design on spatial interaction models. 1: The spatial definition problem.  Environment and Planning A 21(1), 27-46.

Amrhein, C.G., and Flowerdew, R., 1992. The effect of data aggregation on a Poisson regression model of Canadian migration. Environment and Planning A 24(10), 1381-1391.