Perhaps you should try some spelling variations:
nghien cua » nghien cuu, nghiep cua, nghiep vua
hoc doanh » hoa doanh, hoc danh, hoc dan
sach hoc » cach hoc, sach hoi, mach hoc
nhan tai » hang tai, van tai, toan tai
tu sach » thu sach, su sach, te sach
ban hoc » bang hoc, van hoc, bai hoc
va nhan » van nhan, ca nhan, va phan

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach hoc tap, nghien cua ban hoc doanh ((khoa hoc) or (hoa hoc)) xa hoi va nhan tai~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cua ban hoc doanh ((khoa hoc) OR (hoa hoc)) xa hoi va nhan tai.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cua ban hoc doanh ((khoa hoc) or (hoa hoc)) xa hoi va nhan tai*.