Perhaps you should try some spelling variations:
va thieu » va thiet, va hieu, va tieu
hieu van » hieu va, thien van, lieu va
va triet » va thiet, va trien, ve triet
day hanh » day nhanh, day thanh, dao hanh
thuc day » thuc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
hieu ve » hieu va
sach ly » sach y, sach lo, sach ty
cao hoi » cau hoi, co hoi, cao hoc
hanh va » hang va, hanh vi
ly nang » ky nang, ly hang, ly vang
su sach » so sach, vu sach

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 ly nang cao hoi. ((hieu ve) OR (hieu van)) nam thuc day hanh va ((va triet) or (va thieu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ly nang cao hoi. ((hieu ve) OR (hieu van)) nam thuc day hanh va ((va triet) OR (va thieu)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ly nang cao hoi. ((hieu ve) OR (hieu van)) nam thuc day hanh va ((va triet) or (va thieu))".
• Adding a wildcard symbol may retrieve word variants: su sach ly nang cao hoi. ((hieu ve) OR (hieu van)) nam thuc day hanh va ((va triet) or (va thieu))*.