Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
dan hanh » dang hanh, dan khanh, dan thanh
thuc dan » thuc hanh, hoc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
sach doi » sach hoi, sach moi, sach dao
hieu van » thien van, lieu va, hieu ve
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
sang ma » nang ma, sang tao, mang may
tu sach » thu sach, su sach, te sach
vi cua » vai cua, di cua

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 doi ((sang ma) or (tang ma)) hoi. ((hieu van) or (hieu va)) nam thuc dan hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach doi ((sang ma) OR (tang ma)) hoi. ((hieu van) OR (hieu va)) nam thuc dan hanh vi cua viet.
• Adding a wildcard symbol may retrieve word variants: tu sach doi ((sang ma) or (tang ma)) hoi. ((hieu van) or (hieu va)) nam thuc dan hanh vi cua viet*.