Perhaps you should try some spelling variations:
quyen tap » tuyen tap, luyen tap, quyen cap
quyen con » quyen cong, tuyen chon, nguyen con
dung cong » dung trong
thu dung » thuy dung, thuc dung, thu dang
cac khu » cac thu, cac khoi, cac kieu
ve ky » va ky, ke ky
ve li » ve ki
ve ly » ve y, de ly, ke ly

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((quyen tap) or (quyen con)) cac khu đe co ban ((((ve ly) OR (ve ky))) or (ve li)) thu dung cong~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((quyen tap) OR (quyen con)) cac khu đe co ban ((((ve ly) OR (ve ky))) OR (ve li)) thu dung cong*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((quyen tap) or (quyen con)) cac khu đe co ban ((((ve ly) OR (ve ky))) or (ve li)) thu dung cong*".