Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dinh thi » dinh tri
tu sach » thu sach, su sach, te sach
hieu ve » hieu va
duc van » duc va, duc manh, duc phan
thi cua » thai cua, thi cuc, tri cua
y nang » ky nang, ly nang, v nang
nang o » nang co, nang ho, nang ro
cua te » cua tu
o hai » co hai, so hai, o lai

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 o hai. ((hieu ve) or (hieu van)) cao ((duc van) OR (duc tan)) dinh thi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang o hai. ((hieu ve) OR (hieu van)) cao ((duc van) OR (duc tan)) dinh thi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang o hai. ((hieu ve) or (hieu van)) cao ((duc van) OR (duc tan)) dinh thi cua te".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang o hai. ((hieu ve) or (hieu van)) cao ((duc van) OR (duc tan)) dinh thi cua te*.