Wynn gives an example of a balanced incomplete block design for 24 varieties in 56 blocks of three plots each which involves only 24 distinct blocks. It is shown that this design can be obtained from a hierarchic group divisible association scheme, and is one of a set of eight possible designs.
@article{1176344213,
author = {John, Peter W. M.},
title = {A Note on a Finite Population Plan},
journal = {Ann. Statist.},
volume = {6},
number = {1},
year = {1978},
pages = { 697-699},
language = {en},
url = {http://dml.mathdoc.fr/item/1176344213}
}
John, Peter W. M. A Note on a Finite Population Plan. Ann. Statist., Tome 6 (1978) no. 1, pp. 697-699. http://gdmltest.u-ga.fr/item/1176344213/