Perhaps you should try some spelling variations:
nang quan » ban quan, nang suat
hieu suat » hieu luat, hieu qua
quang ban » quang binh, quang tuan, quang tran
tin nang » tin dung, ki nang, thi nang
quan van » luan van, quan va, quan luan
van hieu » cao hieu
ban soat » ban soan, ban sua, ban chat
ban van » ban dan, ban va, tan van

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tin nang quan van hieu suat ) or ( tinh quang ban van ban soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tin nang quan van hieu suat ) OR ( tinh quang ban van ban soat )).
• Adding a wildcard symbol may retrieve word variants: (( tin nang quan van hieu suat ) or ( tinh quang ban van ban soat ))*.