Perhaps you should try some spelling variations:
vanh dai » van dai, vanh tai, lanh dao
tu sach » thu sach, su sach, te sach
ky lang » ky nang, ky dang, tay lang
ky tang » ky nang, ky dang, kho tang
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cao
xuc va » tuc va, luc va, xac va

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

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