@article{Design_Theory-AFP,
  author  = {Chelsea Edmonds and Lawrence C. Paulson},
  title   = {Combinatorial Design Theory},
  journal = {Archive of Formal Proofs},
  month   = {August},
  year    = {2021},
  note    = {\url{https://isa-afp.org/entries/Design_Theory.html},
            Formal proof development},
  ISSN    = {2150-914x},
}