Perhaps you should try some spelling variations:
thanh trung » thanh tung
trung thanh » truong thanh
thiet tach » chiet tach, thien hach, thuat tach
thuat mach » thuat sach, thuat tach, thuyet mach
thang cong » thanh cong, thang long, hang cong
thong cong » trong cong, tong cong, thong thong
dan than » dan chan, ban than, van than
than cau » toan cau, phan cau, than cap

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thiet tach) or (thuat mach)) - thanh trung thanh ((thang cong) OR (thong cong)) dan than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thiet tach) OR (thuat mach)) - thanh trung thanh ((thang cong) OR (thong cong)) dan than cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thiet tach) or (thuat mach)) - thanh trung thanh ((thang cong) OR (thong cong)) dan than cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thiet tach) or (thuat mach)) - thanh trung thanh ((thang cong) OR (thong cong)) dan than cau*.