Perhaps you should try some spelling variations:
nhiet tach » chiet tach
nhung cong » dung cong, thong cong, hang cong
hoc nhiet » hoc thiet, hoc nghien, hoc hien
trung vap » trung cap, trung van, trung lap
trung va » truong va, trang va, trung ha
san toan » van toan, manh toan, xuan toan
dan toan » van toan, dan than, manh toan

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc nhiet tach - hanh ((trung vap) OR (trung va)) nhung cong ((san toan) or (dan toan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc nhiet tach - hanh ((trung vap) OR (trung va)) nhung cong ((san toan) OR (dan toan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc nhiet tach - hanh ((trung vap) OR (trung va)) nhung cong ((san toan) or (dan toan)) cau".
• Adding a wildcard symbol may retrieve word variants: hoc nhiet tach - hanh ((trung vap) OR (trung va)) nhung cong ((san toan) or (dan toan)) cau*.