Hello Ayush,

I am mention here a list of book subjectwise you can go for:

FOR STATISTICS :

• Basic Statistics by: Nagar and Das.
• Mathematical Statistics with Applications by: John E. Fraeund.

FOR GENERAL KNOWLEDGE:

• Hal R Varian
• Hendarson & Quandit
• Mankiw

FOR  MATHEMATICAL ECONOMICS:

• Mathematical Economics by: Sydsaeter and Hammond.
• Mathematics for Economists: Simon and Blume.

FOR MACROECONOMICS:

• Macroeconomics by: M.C. Vaish (for growth models).
• Macroeconomics by: Dornbush and Fischer

FOR MICROECONOMICS:

• Hal. E. Varian
• Exercise book of intermediate Microeconomics by: Hal. E. Varian.

Hope it helps.

Thank you :)