I'll tell. You the best books for NDA -

For mathematics, refer RD AGGARWAL book, and you can use the Arihant book for revision and mock tests. For General Ability, refer Kalpana Rajaram: Spectrum for science and technology, Bipan Chandra for Histor. You can get these books from nearby shops around you or even by any online wesbtites.

Refer to the following website for more detailed information..

https://competition.careers360.com/articles/best-books-prepare-for-nda

Best wishes. Thank you.