Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
nang sang » nang song, nong san
ho thiet » hoc thiet, hoa thiet, hoc thieu
so thiet » soc thiet, hoc thiet, hoa thiet
tang van » dang van, hoang van, trong van
sang va » hang va, song va, sang ma
tan ran » tan tran, tan van, tan san

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((ho thiet) OR (so thiet)) tach - nang sang va nhung cong ((tan ran) or (tang van)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((ho thiet) OR (so thiet)) tach - nang sang va nhung cong ((tan ran) OR (tang van)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((ho thiet) OR (so thiet)) tach - nang sang va nhung cong ((tan ran) or (tang van)) cau".
• Adding a wildcard symbol may retrieve word variants: ((ho thiet) OR (so thiet)) tach - nang sang va nhung cong ((tan ran) or (tang van)) cau*.