For environmental studies preparation for UPSC, aspirants can reference NCERT textbooks, particularly those focused on environmental science. Additionally, standard reference books like "Shankar IAS" are excellent resources. Government reports, such as those from the Ministry of Environment and Wildlife Institute, provide current data and case studies. Online courses and seminars relating to environmental issues can offer contemporary insights. Engaging with online forums and platforms that discuss environmental policies is also beneficial for a well-rounded understanding.