Perhaps you should try some spelling variations:
trinh quan » tinh quang, trinh luat, trinh han
quan lang » quan hoang, gian lang, quan luan
hieu soat » hieu suat, hieu hoat, hieu luat
tien soat » trien hoat, thien hoat, kiem soat
lang van » dang van, tang van, hoang van
van hieu » cao hieu
dung nam » dong nam, dung lam, sung nam
nam toan » nam tan, tam toan, nam thanh

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 lang van hieu soat ) or ( tin dung nam toan tien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh quan lang van hieu soat ) OR ( tin dung nam toan tien soat )).
• Adding a wildcard symbol may retrieve word variants: (( trinh quan lang van hieu soat ) or ( tin dung nam toan tien soat ))*.