Perhaps you should try some spelling variations:
tinh thong » tinh thuong, trinh thong, tinh khong
quang quan » quang tuan, quang uan, quan quan
quan doan » quan hoang, chuan doan, chan doan
hieu soat » hieu suat, hieu hoat, kiem soat
hieu luat » hieu qua
luan kien » xuan kien, luan lien, quan kien
kien ha » kien hoa, kien va, dien hoa

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: (( tinh quang quan doan ((hieu soat) OR (hieu luat)) ) OR ( tinh thong quan luan kien ha ))~.
• Adding a wildcard symbol may retrieve word variants: (( tinh quang quan doan ((hieu soat) or (hieu luat)) ) or ( tinh thong quan luan kien ha ))*.