PRNewswire (25-09-2008). "United Launch Alliance First RS-68A Hot-Fire Engine Test a Success". Nota de premsa. Consulta: 30-09-2008. “Currently, the RS-68 engine can deliver more than 660,000 pounds of sea level thrust and the upgraded RS-68A will increase this to more than 700,000 pounds. The RS-68A also improves on the specific impulse, or fuel efficiency, of the RS-68.”
