Singh, S. &. P. (2019). General studies for civil services preliminary examination 2019. McGraw Hill.
芝加哥风格引文Singh, Surendra & Parmar. General Studies for Civil Services Preliminary Examination 2019. Chennai: McGraw Hill, 2019.
MLA引文Singh, Surendra & Parmar. General Studies for Civil Services Preliminary Examination 2019. McGraw Hill, 2019.
警告：这些引文格式不一定是100％准确.