We completely settle the existence problem for group divisible designs with first and second associates in which the block size is \(3\), and with \(m\) groups each of size \(n\), where \(n, m \geq 3\).
Citation
H. L. Fu, C. A. Rodger, D. G. Sarvate. The Existence of Group Divisible Designs with First and Second Associates, Having Block Size \(3\)[J], Ars Combinatoria, Volume 054. 33-50. .