Ludwig, G. H. (2011). Opening space research: Dreams, technology, and scientific discovery. American Geophysical Union.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रLudwig, George H. Opening Space Research: Dreams, Technology, and Scientific Discovery. Washington, DC: American Geophysical Union, 2011.
एमएलए (9वां संस्करण) प्रशस्ति पत्रLudwig, George H. Opening Space Research: Dreams, Technology, and Scientific Discovery. American Geophysical Union, 2011.
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