Perhaps you should try some spelling variations:
khong luan » thong luan, khong quan, khung luan
tinh khong » tinh khang, tinh huong, benh khong
quan quan » quan quang, quan luan, quang tuan
hieu soat » hieu suat, hieu hoat, hieu luat
tien soan » bien soan, tien hoang, thien toan
van hieu » cao hieu
van tien » toan tien, van tuan

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

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