Perhaps you should try some spelling variations:
thiet tach » chiet tach, thuat tach
thien hach » thien thanh, hien hanh
nhung cong » dung cong, thong cong, hang cong
trang cua » tranh cua, tang cua, thang cua
trung cua » truong cua, trung tuan, trung cap
cong vang » cong lang, cong quang, cong ngang
vang toan » van toan, dang toan, quang 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 ((thiet tach) OR (thien hach)) - hanh ((trang cua) or (trung cua)) nhung cong vang toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thiet tach) OR (thien hach)) - hanh ((trang cua) OR (trung cua)) nhung cong vang toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thiet tach) OR (thien hach)) - hanh ((trang cua) or (trung cua)) nhung cong vang toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thiet tach) OR (thien hach)) - hanh ((trang cua) or (trung cua)) nhung cong vang toan cau*.