DR RANJANA GUPTA. COMPARATIVE STUDY OF PRIMARY CLASSES TEXTBOOKS IN RELATION TO ENVIRONMENTAL CONCEPTS. INTERNATIONAL JOURNAL OF RESEARCH IN COMMERCE, IT, ENGINEERING AND SOCIAL SCIENCES ISSN: 2349-7793 Impact Factor: 6.876, [S. l.], v. 3, n. 9, p. 1–6, 2009. Disponível em: https://www.gejournal.net/index.php/IJRCIESS/article/view/67. Acesso em: 5 dec. 2025.