Perhaps you should try some spelling variations:
dinh thi » dinh tri
tu sach » thu sach, su sach, te sach
cac tac » cac toc, cac bac, cac dac
thi cua » thai cua, thi cuc, tri cua
va dinh » van dinh, va kinh, va tinh
cac tuc » cac toc, cac tu, cac nuoc
hieu va » lieu va
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang

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