Perhaps you should try some spelling variations:
canh trinh » canh tranh, hanh trinh, canh tinh
khang kho » khong kho, khong khoa, khong khi
hang khoa » dung khoa
sach dao » lanh dao
trinh co » trinh do, trinh cong, trinh hoa
vu sach » vu bach, su sach, vu khach
so canh » so sanh, bo canh, so danh

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( vu sach dao ((khang kho) OR (hang khoa)) đong luc ) or ( so canh trinh co khi đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( vu sach dao ((khang kho) OR (hang khoa)) đong luc ) OR ( so canh trinh co khi đong luc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( vu sach dao ((khang kho) OR (hang khoa)) đong luc ) or ( so canh trinh co khi đong luc ))".
• Adding a wildcard symbol may retrieve word variants: (( vu sach dao ((khang kho) OR (hang khoa)) đong luc ) or ( so canh trinh co khi đong luc ))*.