Perhaps you should try some spelling variations:
trinh han » trinh quan
hieu luat » hieu qua
hieu suat » hieu qua
tien soat » trien hoat, thien hoat, kiem soat
han lang » nhan lang, ban lang, ha lang
lang van » dang van, tang van, hoang van
dung lam » dung luan, dung tai, dung dat
lam toan » lam tan, lap toan, tam toan

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( trinh han lang van ((hieu luat) or (hieu suat)) ) or ( tin dung lam toan tien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh han lang van ((hieu luat) OR (hieu suat)) ) OR ( tin dung lam toan tien soat )).
• Adding a wildcard symbol may retrieve word variants: (( trinh han lang van ((hieu luat) or (hieu suat)) ) or ( tin dung lam toan tien soat ))*.