Perhaps you should try some spelling variations:
hieu manh » chieu xanh, hieu nganh, dieu hanh
hanh luan » khanh luan, hang luan, hanh luat
tong cong » trong cong, cong cong, dang cong
dung cong » dung trong
vang toan » van toan, dang toan, quang toan
hoc hieu » hoc thieu, hoc hien, doc hieu
dan toan » van toan, dan than, manh toan

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