Perhaps you should try some spelling variations:
doanh doanh » toan doanh, doanh hoan, doanh thanh
thiet hach » thien hach, thuyet hach, thiet hai
thanh chau » thanh cha, thanh cham, thanh hai
hoc thiet » hoc thieu, hoc thuyet, hoc hien
thanh chu » thanh cha, thanh thu, thanh thuy
doanh va » doan va, doanh tai, doanh cua
cong ban » cong bang, cong san, cong dan
cong tan » cong tac, cong san, cong thanh

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 - doanh doanh va nhung ((cong ban) OR (cong tan)) ((thanh chu) or (thanh chau))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thiet hach - doanh doanh va nhung ((cong ban) OR (cong tan)) ((thanh chu) OR (thanh chau)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thiet hach - doanh doanh va nhung ((cong ban) OR (cong tan)) ((thanh chu) or (thanh chau))".
• Adding a wildcard symbol may retrieve word variants: hoc thiet hach - doanh doanh va nhung ((cong ban) OR (cong tan)) ((thanh chu) or (thanh chau))*.