BibTeX: 
@article{Nash_WilliamsAFP,
author = {Lawrence C. Paulson},
title = {The NashWilliams Partition Theorem},
journal = {Archive of Formal Proofs},
month = may,
year = 2020,
note = {\url{http://isaafp.org/entries/Nash_Williams.html},
Formal proof development},
ISSN = {2150914x},
}
