Perhaps you should try some spelling variations:
trong dang » truong dang, trong dan, trong dong
khoi tinh » hoi tinh, khoa tinh, thoi tinh
khoi kinh » hoc kinh, hoi tinh, khoe sinh
dang toan » dang tran, dan toan, dung toan
kho tinh » khoa tinh, tho tinh, khun tinh
tranh va » tranh van, trang va, trinh va
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.

• If you are trying to use Boolean operators, they must be ALL CAPS: doi ((((khoi tinh) OR (khoi kinh))) OR (kho tinh)) - canh tranh va dung trong dang toan cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi ((((khoi tinh) OR (khoi kinh))) or (kho tinh)) - canh tranh va dung trong dang toan cao~".
• Adding a wildcard symbol may retrieve word variants: doi ((((khoi tinh) OR (khoi kinh))) or (kho tinh)) - canh tranh va dung trong dang toan cao*.