The book considered a standard reference for the General Studies Paper in UPSC is the NCERT series, particularly for its clear and concise presentation of fundamental concepts. In addition to NCERT texts, recommended publications such as Laxmikanth's Indian Polity, Ramesh Singh's Indian Economy, and GC Leong's Physical Geography are widely used. These resources help aspirants develop a comprehensive understanding of topics covered in the syllabus, including History, Geography, and Current Affairs. Utilizing these standard references is crucial for a sound grounding in the subject matter tested in the examination.