Perhaps you should try some spelling variations:
cong thanh » dong thanh, cong trinh, truong thanh
hieu cach » hieu cac, chieu sach, hieu ca
hoc hieu » hoc thieu, hoc hien, doc hieu
thang va » hang va, trang va, thong va
cong tan » cong tac, cong san, cong ty
tang va » trang va, tang van, tang vat
hoa may » hoc may

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu cach - hanh ((tang va) or (thang va)) hang ((cong thanh) OR (cong tan)) hoa may~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu cach - hanh ((tang va) OR (thang va)) hang ((cong thanh) OR (cong tan)) hoa may.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu cach - hanh ((tang va) or (thang va)) hang ((cong thanh) OR (cong tan)) hoa may".
• Adding a wildcard symbol may retrieve word variants: hoc hieu cach - hanh ((tang va) or (thang va)) hang ((cong thanh) OR (cong tan)) hoa may*.