Nearly Balanced Incomplete Block Designs
定义了近乎平衡不完全区组设计，将John和Mitchell的规则图设计扩展到不等重复情形，给出了存在性必要条件、构造方法，并列表展示了五或六品种时的最优设计及其效率。
A class of nearly balanced incomplete block designs is defined. This extends the concept of regular graph designs of John & Mitchell (1977) to the unequally replicated case. Some necessary conditions for the existence of such designs are derived. Methods of construction are given for some special cases. For five or six varieties, the ‘best’ nearly balanced incomplete block designs and their efficiencies are tabulated.