Singh, S. &. P. (2019). General studies for civil services preliminary examination 2019. McGraw Hill.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रSingh, Surendra & Parmar. General Studies for Civil Services Preliminary Examination 2019. Chennai: McGraw Hill, 2019.
एमएलए (9वां संस्करण) प्रशस्ति पत्रSingh, Surendra & Parmar. General Studies for Civil Services Preliminary Examination 2019. McGraw Hill, 2019.
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