Perhaps you should try some spelling variations:
thiet hach » thien hach, thuyet hach, thiet hai
nhung cong » thong cong, hang cong, nhung don
hoc thiet » hoc thieu, hoc thuyet, hoc hien
tranh cua » doanh cua, manh cua
dung cong » dung trong
san toan » van toan, dan toan, manh toan
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 hach - canh tranh cua ((nhung cong) or (dung cong)) san toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thiet hach - canh tranh cua ((nhung cong) OR (dung cong)) san toan cao.
• Adding a wildcard symbol may retrieve word variants: hoc thiet hach - canh tranh cua ((nhung cong) or (dung cong)) san toan cao*.