BibTeX: 
@article{Stewart_ApolloniusAFP,
author = {Lukas Bulwahn},
title = {Stewart's Theorem and Apollonius' Theorem},
journal = {Archive of Formal Proofs},
month = jul,
year = 2017,
note = {\url{http://isaafp.org/entries/Stewart_Apollonius.html},
Formal proof development},
ISSN = {2150914x},
}
