Wd. Wei et Jy. Xu, CONSTRUCTION OF PBIB DESIGNS BY USING DESCARTES PRODUCT OF KNOWN PBIBDESIGNS, Chinese annals of mathematics. Ser. B, 14(2), 1993, pp. 245-252
The author discuss the Descartes product of a number of association sc
hemes, introduce the Descartes product of t(t greater-than-or-equal-to
2) given PBIB designs and, finally, solve the general problem: How to
obtain a new PBIB design from any t(t greater-than-or-equal-to 2) PBI
B designs?