Perhaps you should try some spelling variations:
quang quan » quang tuan, quang uan, quan quan
tinh vuong » thinh vuong, tinh huong, minh vuong
vuong quan » luong quan, cuong quan, luong quang
hieu soat » hieu hoat, hieu luat, hieu so
hieu suat » hieu luat, hieu qua
kiem soat » kiem toan
quan van » luan van, quan va, quan luan
van kiem » va kiem, van kien, van hieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh quang quan van ((hieu soat) OR (hieu suat)) ) or ( tinh vuong quan van kiem soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh quang quan van ((hieu soat) OR (hieu suat)) ) OR ( tinh vuong quan van kiem soat )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh quang quan van ((hieu soat) OR (hieu suat)) ) or ( tinh vuong quan van kiem soat ))".
• Adding a wildcard symbol may retrieve word variants: (( tinh quang quan van ((hieu soat) OR (hieu suat)) ) or ( tinh vuong quan van kiem soat ))*.