Perhaps you should try some spelling variations:
thiet hach » thien hach, thuyet hach, thiet hai
phan xuong » phan cong
hoc thiet » hoc thieu, hoc thuyet, hoc hien
manh dung » manh hung, manh tung, anh dung
dung phan » dung nhan, dung luan, dung ha
dung toan » dung doanh, dung thang, dung thanh
cong tan » cong tac, cong san, cong thanh
phan lap » phan dau

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 - manh dung phan xuong ((cong tan) or (dung toan)) phan lap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thiet hach - manh dung phan xuong ((cong tan) OR (dung toan)) phan lap.
• Adding a wildcard symbol may retrieve word variants: hoc thiet hach - manh dung phan xuong ((cong tan) or (dung toan)) phan lap*.