Nike Vaporfly shoes are not banned but Eliud Kipchoge's are - BBC Sport
By Wearing Vaporfly Prototypes, Eliud Kipchoge, Galen Rupp, & Shalane Flanagan Are All Guilty of Mechanical Doping in 2016 - Will Anything Be Done About It? - LetsRun.com
Technological doping: The science of why Nike Alphaflys were banned from the Tokyo Olympics | BBC Science Focus Magazine