Perhaps you should try some spelling variations:
khong luan » khong quan, khung luan, phong luan
thong luan » thong quan, tong luan, thong xuan
trinh han » trinh quan
han quang » phan quang, hang quang, than quang
quang van » quang ban, quan van, quang uan
hieu soat » hieu suat, hieu hoat, hieu luat
tien soat » trien hoat, thien hoat, kiem soat
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: (( trinh han quang van hieu soat ) or ( tinh ((khong luan) or (thong luan)) van tien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh han quang van hieu soat ) OR ( tinh ((khong luan) OR (thong luan)) van tien soat )).
• Adding a wildcard symbol may retrieve word variants: (( trinh han quang van hieu soat ) or ( tinh ((khong luan) or (thong luan)) van tien soat ))*.