WILLIAMS, G. A., BOLEN, M. C., & DOERHOFF Ray B. (1973). Challenges to science physical science. Wbster Division, McGraw-Hill Book Company.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रWILLIAMS, George A., Max C. BOLEN, और DOERHOFF Ray B. Challenges to Science Physical Science. New York: Wbster Division, McGraw-Hill Book Company, 1973.
एमएलए (9वां संस्करण) प्रशस्ति पत्रWILLIAMS, George A., et al. Challenges to Science Physical Science. Wbster Division, McGraw-Hill Book Company, 1973.
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