Fybblog.com here gave you link to download NIOS 337 Tourism book in Pdf format. Both Hindi Medium and English Medium books are available here to download.
English Medium
Tourism_Book-01
Tourism_Book-02
Tourism_Book-03
Tourism_Book-04
Hindi Medium
Tourism_Book-01_hindi
Tourism_Book-02_hindi
Tourism_Book-03_hindi
Tourism_Book-04_hindi