Perhaps you should try some spelling variations:
su sach » so sach, vu sach
hieu ve » hieu van
hieu va » lieu va, hieu qua
vai hoa » van hoa, dai hoa, lai hoa
y nang » ky nang, ly nang, v nang
nam tu » nam thu, nam thuc
va dan » ca dan, va dao, va dau
va hoa » van hoa, va hoc, ma hoa
x hoi » xa hoi, o hoi, x ho

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 y nang x hoi. ((hieu ve) or (hieu va)) nam tu va dan ((vai hoa) OR (va hoa)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang x hoi. ((hieu ve) OR (hieu va)) nam tu va dan ((vai hoa) OR (va hoa)) viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang x hoi. ((hieu ve) or (hieu va)) nam tu va dan ((vai hoa) OR (va hoa)) viet".
• Adding a wildcard symbol may retrieve word variants: su sach y nang x hoi. ((hieu ve) or (hieu va)) nam tu va dan ((vai hoa) OR (va hoa)) viet*.