Hi Gaurav,

Here are the best biology reference books for class 9

S.CHAND BIOLOGY

PEARSON FOUNDATION SERIES

MAC GRAW HILL

ARIHANT ALL IN ONE SCIENCE

MTG BIOLOGY

These are the best in the market. It is advisable that you have your basics right first with your NCERT books which is the mother of all the books in the market.Once you are clear in the basics and then you can refer the other books.

Hope this helps

All the best