The following publications are possibly variants of this publication:
- Lambda-fold 2-perfect 6-cycle systems in equipartite graphsElizabeth J. Billington, Dean G. Hoffman. DM, 311(21):2423-2427, 2011. [doi]
- 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 4-wheel systems into lambda-fold bowtie systemsElizabeth J. Billington. ajc, 22:265-286, 2000. [doi]
- Lambda-fold 3-perfect 9-cycle systemsPeter Adams, Elizabeth J. Billington. arscom, 44, 1996.