Perhaps you should try some spelling variations:
hieu nganh » vien nganh, hiem ngan, nghiep nganh
hieu manh » chieu xanh, dieu hanh, hien hanh
hanh tang » hanh trang, anh tang, hanh mang
cong vang » cong lang, cong quang, cong ngang
cong van » cong san, song van, cong tan
quan tap » quan tai, quan lap, quan tam
tang va » trang va, tang van, thang va
va hang » van hang, va nang, va lang

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 manh) or (hieu nganh)) - hanh tang va hang ((cong van) OR (cong vang)) quan tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu manh) OR (hieu nganh)) - hanh tang va hang ((cong van) OR (cong vang)) quan tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu manh) or (hieu nganh)) - hanh tang va hang ((cong van) OR (cong vang)) quan tap".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu manh) or (hieu nganh)) - hanh tang va hang ((cong van) OR (cong vang)) quan tap*.