Hello,

As you have not specified the subject and there are many

• Anthropology
• Archaeology
• Education
• English
• Economic
• French
• Geography
• German
• Hindi
• History
• Library science
• Maths
• Political science
• Public administration

There are many subjects to choose from

So I can tell you some reference books you can use.

And please specify the subject you want to know more about.

• Majumdar Ray : an advanced history of India
• Tripathi R S : ancient India
• Ray Choudhury H C : political history of ancient India
• Dr I A Khan : environmental law
• MP Sharma : public administration and theory and practice
• White: introduction to study of public administration
• Willoughby : principle of public administration

These are some books that might help.

Please comment below you you want to know about some specific subject

Best of luck!!