The following books and resources, in general, should not be studied as a whole. Cost-Benefit is less for these books. However, these books can be referred to get the whole picture of a few topics. Other than this aspect, it is better to avoid these.
Any Coaching Material should be read with Caution.
Based on the cost-benefit analysis, this magazine is not required. Hindu paper, PIB website and Yojana magazines are more than sufficient. This magazine focusses more on rural development and this topic is just a part of the syllabus.
Indian Economy by Sanjiv Verma
The book is simple and easy to understand. However, it is not sufficient. You still should study NCERT books. Then prepare an Economic survey and budget. Finally, go through all current affairs. If you want to get a gist of the Indian Economy, then you can read this book. But it is not required if you can understand NCERT books.
Shankar IAS Book on Environment and Ecology
Many people refer to this book. Private coaching materials should be read with very cautious. Shankar IAS book is an amalgamation of internet articles. It has more content than is required for IAS preparation. It has become a bulky book over a period of time.
NCERT Class XI Physical Geography Last two chapters and Class XII biology last 4 chapters, latest current affairs related to the environment, legislation (national and international), court judgments are to be studied to get maximum advantage in this area.