Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, tu cach
vai cua » dai cua, hai cua, lai cua
dau vai » dau va, dau hai, dau tai
cac tuc » cac toc, cac tu, cac tac
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
te sach » toc sach
ma hoi » mai hoi, xa hoi, ma hoa
tuc va » thuc va, truc va, tuc xa
va dau » va dao

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) OR (te sach)) ky nang ma hoi. ((hieu ve) or (hieu qua)) cac tuc va dau vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ky nang ma hoi. ((hieu ve) OR (hieu qua)) cac tuc va dau vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (te sach)) ky nang ma hoi. ((hieu ve) or (hieu qua)) cac tuc va dau vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (te sach)) ky nang ma hoi. ((hieu ve) or (hieu qua)) cac tuc va dau vai cua tre*.