Perhaps you should try some spelling variations:
hanh trinh » canh tranh, hanh chinh
duong xanh » duong manh, duong van, duong sach
hieu sang » chieu sang, hieu quang, nhieu tang
hieu lang » chieu sang, hieu quang, nhieu tang
duong anh » duong manh, duong vanh, dong anh
trinh va » trinh van, trinh vat, trinh ve
toan cau » toan cao, toan ban, toan tap
va dung » van dung, va duong, vat dung

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) or (hieu lang)) - hanh trinh va dung ((duong anh) OR (duong xanh)) toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu lang)) - hanh trinh va dung ((duong anh) OR (duong xanh)) toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) or (hieu lang)) - hanh trinh va dung ((duong anh) OR (duong xanh)) toan cau".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) or (hieu lang)) - hanh trinh va dung ((duong anh) OR (duong xanh)) toan cau*.