中国科学院数学与系统科学研究院期刊网
Consistent Nonnegative Estimates of Variance Components
Li-wen Xu, Song-gui Wang, Jian-hong Shi
Acta Mathematicae Applicatae Sinica(English Series) . 2010, (2): 177 -186 .  DOI: 10.1007/s10255-009-5103-7