Perhaps you should try some spelling variations:
trinh han » trinh quan
hieu suat » hieu luat, 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
van hieu » cao hieu
dung nam » dong nam, dung lam, sung nam
van tien » toan tien, van tuan
nam van » nam dan, nam va, pham van

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 suat ) or ( tin dung nam van tien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh han lang van hieu suat ) OR ( tin dung nam van tien soat )).
• Adding a wildcard symbol may retrieve word variants: (( trinh han lang van hieu suat ) or ( tin dung nam van tien soat ))*.