Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
thuc dan » thuc hanh, hoc dan, thuc vat
thuc va » thuc vat, thuc day
sach ty » sach y, sach tu, sach thu
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
sang ma » tang ma, nang ma, sang tao
vi cua » vai cua, di cua
ve nam » he nam, va nam, le nam

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty ((sang ma) or (mang may)) hoi. hieu ve nam ((thuc va) OR (thuc dan)) hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((sang ma) OR (mang may)) hoi. hieu ve nam ((thuc va) OR (thuc dan)) hanh vi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((sang ma) or (mang may)) hoi. hieu ve nam ((thuc va) OR (thuc dan)) hanh vi cua viet".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((sang ma) or (mang may)) hoi. hieu ve nam ((thuc va) OR (thuc dan)) hanh vi cua viet*.