Perhaps you should try some spelling variations:
va triet » va trien, ve triet, cua triet
nam thuc » nam thuoc, am thuc, nam thu
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
ly nang » ky nang, ly hang, ly vang
hanh va » hang va, hanh vi
hieu ve » hieu va, hieu van
sach ly » sach y, sach lo, sach ty
thuc va » thuc vat, thuc dan, thuc day
ve nam » he nam, va nam, le nam
ma hoi » mai hoi, ma hoa, me hoi
thiet » thieu

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