Perhaps you should try some spelling variations:
tinh thong » tinh thuong, trinh thong, tinh khong
thong xuan » thong quan, thong luan, thong quang
hieu soat » hieu suat, hieu hoat, hieu luat
kien soat » kiem soat, bien soan, kien hoa
quan lan » quan lang, quan van, quan lap
van hieu » cao hieu
xuan van » luan van, quan van, xuan can
van kien » van tien, van hien, van chien

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 lan) OR (quan luan)) van hieu soat ) or ( tinh thong xuan van kien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh ((quan lan) OR (quan luan)) van hieu soat ) OR ( tinh thong xuan van kien soat )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh ((quan lan) OR (quan luan)) van hieu soat ) or ( tinh thong xuan van kien soat ))".
• Adding a wildcard symbol may retrieve word variants: (( tinh ((quan lan) OR (quan luan)) van hieu soat ) or ( tinh thong xuan van kien soat ))*.