Perhaps you should try some spelling variations:
dung quan » dung quang, dung luan, luong quan
hieu suat » hieu luat, hieu qua
tinh hong » tinh huong, tinh khong, tinh phong
hong quan » thong quan, tong quan, uong quan
quan hanh » quan thanh, quang thanh, quang khanh
hanh bien » hanh kien, thanh vien, thanh nien
quan cao » quang cao, quan cau, quan ao
bien so » bien doi

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tin dung quan cao hieu suat ) or ( tinh hong quan hanh bien so ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tin dung quan cao hieu suat ) OR ( tinh hong quan hanh bien so )).
• Adding a wildcard symbol may retrieve word variants: (( tin dung quan cao hieu suat ) or ( tinh hong quan hanh bien so ))*.