Perhaps you should try some spelling variations:
thiet dang » thien dang, nhiet nang, thien bang
nhung cong » dung cong, thong cong, hang cong
trinh vat » trinh van, trinh luat, sinh vat
trang va » tran van, hang va
cong van » cong vang, cong san, song van
van toan » van tuan, van tan, van thanh
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 dang) OR (nhiet dong)) - hanh ((trinh vat) or (trang va)) nhung cong van toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thiet dang) OR (nhiet dong)) - hanh ((trinh vat) OR (trang va)) nhung cong van toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thiet dang) OR (nhiet dong)) - hanh ((trinh vat) or (trang va)) nhung cong van toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thiet dang) OR (nhiet dong)) - hanh ((trinh vat) or (trang va)) nhung cong van toan cau*.