Perhaps you should try some spelling variations:
thieu xanh » hieu manh, thien anh, thien danh
chieu xanh » chieu sach, chieu sang, chieu tinh
nhung cong » dung cong, thong cong, hang cong
hanh tang » hanh trang, hanh mang, hanh tung
anh tang » anh bang, anh dang, anh nang
cong dan » cong san, cong tan, huong dan
dan toan » van toan, dan than, manh toan
toan cau » 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: hoc ((thieu xanh) OR (chieu xanh)) - ((hanh tang) or (anh tang)) va nhung cong dan toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu xanh) OR (chieu xanh)) - ((hanh tang) OR (anh tang)) va nhung cong dan toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu xanh) OR (chieu xanh)) - ((hanh tang) or (anh tang)) va nhung cong dan toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu xanh) OR (chieu xanh)) - ((hanh tang) or (anh tang)) va nhung cong dan toan cau*.