Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
te sach » toc sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
duc ban » duc tan, dua ban, duc man
duc van » duc va, duc tan, duc manh
hanh va » hang va, hanh vi
va cua » va chua, via cua, ca cua
cua te » cua tu
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky nang x hoi. ((hieu van) or (hieu va)) cao ((duc ban) OR (duc van)) hanh va cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang x hoi. ((hieu van) OR (hieu va)) cao ((duc ban) OR (duc van)) hanh va cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang x hoi. ((hieu van) or (hieu va)) cao ((duc ban) OR (duc van)) hanh va cua te".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang x hoi. ((hieu van) or (hieu va)) cao ((duc ban) OR (duc van)) hanh va cua te*.