BibTeX: 
@article{MengerAFP,
author = {Christoph Dittmann},
title = {Menger's Theorem},
journal = {Archive of Formal Proofs},
month = feb,
year = 2017,
note = {\url{http://isaafp.org/entries/Menger.shtml},
Formal proof development},
ISSN = {2150914x},
}
