TY  - RPRT
TI  - Change-in-ratio estimators for populations with more than two subclasses
AU  - Mark S. Udevitz
AU  - Kenneth H. Pollock
PY  - 1991
DO  - 10.2307/2532404
UR  - https://pubs.usgs.gov/publication/70180936
ID  - 70180936
ER  -