Perhaps you should try some spelling variations:
tinh khong » tinh khang, tinh huong, benh khong
dung quan » dung quang, dung luan, luong quan
hieu soat » hieu suat, hieu hoat, hieu luat
kien soat » kiem soat, bien soan, kien hoa
quan vo » quan vi, quan ve, quan ao
vo hieu » co hieu, va hieu, cao hieu
quan va » quan vi, quan ha, luan va
lan van » luan van, lang van, tan van

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh dung quan vo hieu soat ) OR ( tinh khong ((quan va) OR (lan van)) kien soat ))~.
• Adding a wildcard symbol may retrieve word variants: (( trinh dung quan vo hieu soat ) or ( tinh khong ((quan va) or (lan van)) kien soat ))*.