Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
hieu van » hieu va, thien van, lieu va
tinh vai » tinh va, tinh hai, tinh bai
thuc dan » thuc hanh, hoc dan, thuc vat
thuc va » thuc vat, thuc day
te sach » toc sach
tang ma » mang may, tang van
sang ma » nang ma, sang tao, mang may
van lam » van nam
vai va » mai va, dai va, hai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach y ((sang ma) OR (tang ma)) hoi. hieu van lam ((thuc va) or (thuc dan)) tinh vai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y ((sang ma) OR (tang ma)) hoi. hieu van lam ((thuc va) OR (thuc dan)) tinh vai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach y ((sang ma) OR (tang ma)) hoi. hieu van lam ((thuc va) or (thuc dan)) tinh vai va triet".
• Adding a wildcard symbol may retrieve word variants: te sach y ((sang ma) OR (tang ma)) hoi. hieu van lam ((thuc va) or (thuc dan)) tinh vai va triet*.