Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
hanh trinh » canh tranh
hieu sang » chieu sang, hieu lang, hieu quang
cua nhung » va nhung
cong hach » cong sach, cong thanh, cong khanh
doc hieu » toc thieu, hoc thieu, hoc hien
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: doc hieu sang - ((hanh trinh) or (hanh chinh)) cua nhung cong hach ((toan cau) OR (toan cao))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sang - ((hanh trinh) OR (hanh chinh)) cua nhung cong hach ((toan cau) OR (toan cao)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu sang - ((hanh trinh) or (hanh chinh)) cua nhung cong hach ((toan cau) OR (toan cao))".
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - ((hanh trinh) or (hanh chinh)) cua nhung cong hach ((toan cau) OR (toan cao))*.