Perhaps you should try some spelling variations:
hieu nganh » vien nganh, hiem ngan, nghiep nganh
nhung cong » dung cong, thong cong, nhung don
hieu manh » chieu xanh, dieu hanh, hien hanh
hanh tang » hanh trang, anh tang, hanh mang
hang cong » dang cong, hang nong, bang cong
toan cau » toan cao, toan ban, toan tap
tang va » trang va, tang van, thang va

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