Elizabeth J. Billington, Dean G. Hoffman. The number of repeated blocks in balanced ternary designs with block size three II. Discrete Mathematics, 92(1-3):25-37, 1991. [doi]
@article{BillingtonH91,
title = {The number of repeated blocks in balanced ternary designs with block size three II},
author = {Elizabeth J. Billington and Dean G. Hoffman},
year = {1991},
doi = {10.1016/0012-365X(91)90264-3},
url = {http://dx.doi.org/10.1016/0012-365X(91)90264-3},
researchr = {https://researchr.org/publication/BillingtonH91},
cites = {0},
citedby = {0},
journal = {Discrete Mathematics},
volume = {92},
number = {1-3},
pages = {25-37},
}