@BOOK{NAP10518, author = "Transportation Research Board and National Research Council", title = "Aeronautics Research and Technology for 2050: Letter Report", doi = "10.17226/10518", url = "https://nap.nationalacademies.org/catalog/10518/aeronautics-research-and-technology-for-2050-letter-report", year = 2002, publisher = "The National Academies Press", address = "Washington, DC" }