8Wang H, Liu Y M, Qi Z M, Wang S Y, Liu S X, Li X, Wang H J, Wang X L, Xia X C, Zhu X Q. The estimation of soil trace elements distribution and soil-plant-animal continuum in relation to trace elements status of sheep in Huangcheng area of Qilian Mountain Grassland, China. Journal of Integrative Agriculture, 9014, 13( 1 ) : 140-147. 被引量：1
9Goodman L A.Comment: On respondent-driven sampling and snowball sampling in hard-to-reach populations and snowball sampling not in hard-to reach populations. Sociological Methodology, 2011, 41 ( 1 ) : 347- 353. 被引量：1
10Charnes A, Cooper W W, Phodes E. Measuring the Efficiency of DMU. European Journal of Operational Research, 1978, (2) : 429-444. 被引量：1
