Panek, R. (2019). The trouble with gravity: Solving the mystery beneath our feet. Houghton Mifflin Harcourt.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रPanek, Richard. The Trouble with Gravity: Solving the Mystery Beneath Our Feet. Boston ; New York: Houghton Mifflin Harcourt, 2019.
एमएलए (8वां संस्करण) प्रशस्ति पत्रPanek, Richard. The Trouble with Gravity: Solving the Mystery Beneath Our Feet. Houghton Mifflin Harcourt, 2019.
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