Perhaps you should try some spelling variations:
thien van » thi van
ban thanh » ban hanh, ban hang
dieu tra » dieu tri, kiem tra
hieu van » hieu va, lieu va, hieu ve
tu sach » thu sach, su sach, te sach
duc ban » duc tan, duc van, dua ban
cac duc » cac du, cao duc, cac dac
sach tu » sach thu, cach tu, sach ty
nang xa » nang x, lang xa, nang ma
tu nang » tru nang, tu nong, tu nano

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 tu nang xa hoi. ((hieu van) or (thien van)) cac duc ban thanh ((dieu cua) OR (dieu tra)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu nang xa hoi. ((hieu van) OR (thien van)) cac duc ban thanh ((dieu cua) OR (dieu tra)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach tu nang xa hoi. ((hieu van) or (thien van)) cac duc ban thanh ((dieu cua) OR (dieu tra)) te".
• Adding a wildcard symbol may retrieve word variants: tu sach tu nang xa hoi. ((hieu van) or (thien van)) cac duc ban thanh ((dieu cua) OR (dieu tra)) te*.