Perhaps you should try some spelling variations:
thiet tach » chiet tach, thien hach, thuat tach
hoc thiet » hoc thieu, hoc thuyet, hoc hien
dung cong » dung trong
tram van » tran van, trang van, tranh van
cong dan » cong san, cong tan, huong dan
dan than » dan chan, ban than, van than
than cau » toan cau, phan cau, than cap
tam van » nam van, tom van, pham van
dam van » dao van, nam van, pham van

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 thiet tach - hanh ((tram van) OR (((tam van) OR (dam van)))) dung cong dan than cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thiet tach - hanh ((tram van) or (((tam van) OR (dam van)))) dung cong dan than cau~".
• Adding a wildcard symbol may retrieve word variants: hoc thiet tach - hanh ((tram van) or (((tam van) OR (dam van)))) dung cong dan than cau*.