Perhaps you should try some spelling variations:
su sach » so sach, vu sach
dan vai » dan va, dan tai, dan vat
hieu va » lieu va, hieu qua
hieu ve » hieu van
vu nang » vuc nang, va nang, vu dang
vai hoa » van hoa, va hoa, dai hoa
nam tu » nam thu, nam thuc
va dan » ca dan, va dao, va dau
v nang » va nang, van nang, voi nang
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 ((v nang) OR (vu nang)) x hoi. ((hieu ve) or (hieu va)) nam tu va dan vai hoa viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((v nang) OR (vu nang)) x hoi. ((hieu ve) OR (hieu va)) nam tu va dan vai hoa viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((v nang) OR (vu nang)) x hoi. ((hieu ve) or (hieu va)) nam tu va dan vai hoa viet".
• Adding a wildcard symbol may retrieve word variants: su sach ((v nang) OR (vu nang)) x hoi. ((hieu ve) or (hieu va)) nam tu va dan vai hoa viet*.