एपीए उद्धरण

Usha, M. (1993). Sampling schemes providing unbiased ratio and regression estimators. Dept of statistics, University of Kerala.

शिकागो स्टाइल उद्धरण

Usha, M.S. Sampling Schemes Providing Unbiased Ratio and Regression Estimators. Thiruvananthapuram: Dept of statistics, University of Kerala, 1993.

एमएलए उद्धरण

Usha, M.S. Sampling Schemes Providing Unbiased Ratio and Regression Estimators. Dept of statistics, University of Kerala, 1993.