Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
nhung cong » dung cong, hang cong, nhung don
thong cong » trong cong, tong cong, thong thong
hoi hieu » hoi phieu, hoi tieu, moi hieu
sinh cua » manh cua, dinh cuu, sinh va
toan cau » toan ban, toan tap, toan tai
toan cao » toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoi hieu quang - nhan sinh cua ((nhung cong) OR (thong cong)) dan ((toan cau) or (toan cao))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoi hieu quang - nhan sinh cua ((nhung cong) OR (thong cong)) dan ((toan cau) OR (toan cao)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoi hieu quang - nhan sinh cua ((nhung cong) OR (thong cong)) dan ((toan cau) or (toan cao))".
• Adding a wildcard symbol may retrieve word variants: hoi hieu quang - nhan sinh cua ((nhung cong) OR (thong cong)) dan ((toan cau) or (toan cao))*.