Perhaps you should try some spelling variations:
trinh quan » tinh quang, trinh luat, trinh han
dinh quang » tinh quang, minh quang, dinh duong
hieu soat » hieu suat, hieu hoat, hieu luat
kien soat » kiem soat, bien soan, kien hoa
van hieu » cao hieu
van kien » van tien, van hien, van chien
luan » lan
qluan » qlan

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

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