1. Billington, Elizabeth J.,More balanced ternary designs with block size three. Discrete Math.39 (1982), 9–21.
2. Billington, Elizabeth J.,On lambda coverings of pairs by triples, repeated elements allowed in triples. Utilitas Math.21C (1982), 187–203.
3. Billington, Elizabeth J.,Balanced n-ary designs: a combinatorial survey and some new results. InProc. XI Australasian Conf. in Combinatorial Math. and Computing. Ars Combinatoria17A (1984), 37–72.
4. Lecture Notes in Math.;Elizabeth J. Morgan,1980
5. Ray-Chaudhuri, D. K. andWilson, R. M.,Solution of Kirkman's schoolgirl problem. InCombinatorics (Proc. Symp. Pure Math., Vol. XIX, Univ. California, Los Angeles, Calif., 1968), Amer. Math. Soc., Providence, R.I., 1971, pp. 187–203.