Foust, Jeff (11 de septiembre de 2020). «ULA studying long-term upgrades to Vulcan». Consultado el 4 de marzo de 2021. «"ACES work has its fingerprints in our new version of Centaur, the Centaur 5 we're fielding with Vulcan. Those studies five, eight years ago certainly served us well, and it put us on a good path forward here for the evolution of our upper stages. We will continue to evolve our upper stage to meet the needs of the market going forward".»