Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
thu sach » tu sach, thuoc sach, thu hoach
vanh dai » van dai, vanh tai, lanh dao
sua viet » su viet, cua viet, lua viet
kho tang » cao tang
tang xa » trang xa, tang ma, lang xa
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
dai sua » dai cua
tuc va » truc va, tuc xa, duc va
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (thuat sach)) kho tang xa hoi. hieu va cam ((tuc va) OR (thuc va)) vanh dai sua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuat sach)) kho tang xa hoi. hieu va cam ((tuc va) OR (thuc va)) vanh dai sua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (thuat sach)) kho tang xa hoi. hieu va cam ((tuc va) OR (thuc va)) vanh dai sua viet".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuat sach)) kho tang xa hoi. hieu va cam ((tuc va) OR (thuc va)) vanh dai sua viet*.