Perhaps you should try some spelling variations:
nghien cua » nghien cuu, nghiep cua, nghiep vua
hoa doanh » toan doanh, hoa dan
doanh hoa » doanh khoa, doanh hoan, danh hoa
sach hoc » cach hoc, sach hoi, mach hoc
cong hoa » dong hoa, dong hoc, hang hoa
tu sach » thu sach, su sach, te sach
va nhan » van nhan, va phan, va nha
hoc xa » hoc ma

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach hoc tap, nghien cua cong hoa doanh hoa hoc xa hoi ((va nhan) OR (ca nhan)) van~".
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cua cong hoa doanh hoa hoc xa hoi ((va nhan) OR (ca nhan)) van*.