Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
duc manh » suc manh, duc anh, duc minh
dinh thi » dinh tri
hieu van » hieu va, thien van, lieu va
hieu ve » hieu va
duc van » duc va, duc tan, 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: thu sach y nang o hai. ((hieu ve) or (hieu van)) cao ((duc van) or (duc manh)) dinh thi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang o hai. ((hieu ve) OR (hieu van)) cao ((duc van) OR (duc manh)) dinh thi cua te.
• Adding a wildcard symbol may retrieve word variants: thu sach y nang o hai. ((hieu ve) or (hieu van)) cao ((duc van) or (duc manh)) dinh thi cua te*.