Perhaps you should try some spelling variations:
thieu xanh » chieu xanh, hieu manh, thien anh
chieu sach » chinh sach, chiet tach, chieu sang
thong cong » trong cong, tong cong, thong thong
canh tinh » hanh tinh, manh tinh, canh tranh
cong dan » cong san, cong tan, huong dan
dan toan » van toan, dan than, manh toan
toan cao » toan ban, toan tap
tinh he » trinh he, hinh he, tinh ha

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 sach)) - canh tinh he thong cong dan toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu xanh) OR (chieu sach)) - canh tinh he thong cong dan toan cao.
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu xanh) or (chieu sach)) - canh tinh he thong cong dan toan cao*.