Essential books recommended for UPSC aspirants vary depending on the subjects of focus but typically include standard texts for General Studies, such as NCERT textbooks for foundational knowledge. For current affairs, publications like The Hindu and Yojana are highly regarded. Subject-specific books, including by authors such as Laxmikant for Polity or Ramesh Singh for Economy, are also essential. Additionally, reference materials for optional subjects should be sourced from credible authors and latest editions to ensure comprehensive coverage of the syllabus and updated information.