Perhaps you should try some spelling variations:
nghien cua » nghien cuu, nghiep cua, nghiep vua
hoc doanh » hoa doanh, hoc danh, hoc dan
van thanh » ban thanh, van tuan
sach dao » lanh dao
cong hoc » dong hoc, cong hoa, cong coc
hoan hoc » toan hoc, hoang hoa, khoan hoi
so sach » so sanh, bo sach, co sach
dao tai » dao thai, dao tao, cao tai
hai van » thai van, ha van, hai tan
ma hai » ta hai, va hai, xa hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach dao tai, nghien cua cong hoc doanh ((hoan hoc) or (hoa hoc)) ma hai van thanh san~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach dao tai, nghien cua cong hoc doanh ((hoan hoc) OR (hoa hoc)) ma hai van thanh san.
• Adding a wildcard symbol may retrieve word variants: so sach dao tai, nghien cua cong hoc doanh ((hoan hoc) or (hoa hoc)) ma hai van thanh san*.