Perhaps you should try some spelling variations:
hoc thiet » hoc thieu, hoc thuyet, hoc hien
trang vap » trang vai, trang van, tran van
dung cong » dung trong
hoc viet » hoc hien
trang va » tran van, hang va
cong san » cong tac
san toan » van toan, dan toan, manh 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 viet) or (hoc thiet)) tach - hanh ((trang vap) OR (trang va)) dung cong san toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc viet) OR (hoc thiet)) tach - hanh ((trang vap) OR (trang va)) dung cong san toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc viet) or (hoc thiet)) tach - hanh ((trang vap) OR (trang va)) dung cong san toan cau".
• Adding a wildcard symbol may retrieve word variants: ((hoc viet) or (hoc thiet)) tach - hanh ((trang vap) OR (trang va)) dung cong san toan cau*.