Perhaps you should try some spelling variations:
thanh trung » thanh tung
thien danh » thien anh, thien dang, thien thanh
duong manh » duong van
hien danh » hien hanh, hien nhanh, hien khanh
chua xang » chua nang, chuc nang, chu bang
manh toan » thanh toan, anh tuan, tinh toan
chu nang » chuc nang, chua nang, cuu nang
toan cau » toan cao, toan ban, toan tap

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: hoc ((hien danh) OR (thien danh)) - thanh trung ((chua xang) OR (chu nang)) duong manh toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hien danh) OR (thien danh)) - thanh trung ((chua xang) or (chu nang)) duong manh toan cau~".
• Adding a wildcard symbol may retrieve word variants: hoc ((hien danh) OR (thien danh)) - thanh trung ((chua xang) or (chu nang)) duong manh toan cau*.