The following publications are possibly variants of this publication:
- The spectrum for lambda-fold 2-perfect 6-cycle systemsElizabeth J. Billington, Charles C. Lindner. ejc, 13(1):5-14, 1992. [doi]
- The metamorphosis of lambda-fold K3, 3-designs into lambda-fold 6-cycle systemsElizabeth J. Billington, Gaetano Quattrocchi. arscom, 64:65, 2002.
- The spectrum for 2-perfect bowtie systemsElizabeth J. Billington, Charles Curtis Lindner. DM, 135(1-3):61-68, 1994. [doi]