Perhaps you should try some spelling variations:
thien hoat » trien hoat, thien thuat, tien hoa
tinh dung » trinh dung, tin dung, tinh huong
dung quan » dung quang, dung luan, luong quan
hieu suat » hieu luat, hieu qua
quang cua » quan cua, quang tuan, quang huy
tien soat » trien hoat, kiem soat, tien hoa
quan va » quan vi, quan ha, luan va
va hieu » van hieu, va dieu, va hien
cua van » cua ban, cua vat, cua dan

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

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