中国科学院数学与系统科学研究院期刊网
Incomplete Group Divisible Designs with Block Size Four and General Index
Li-dong Wang, Hai-rong Kong, Hong-juan Liu
Acta Mathematicae Applicatae Sinica(English Series) . 2011, (3): 407 -418 .  DOI: 10.1007/s10255-011-0080-z