Perhaps you should try some spelling variations:
sach tranh » canh tranh
tranh cong » thanh cong, trinh cong, tran cong
khanh hoa » thanh hoa
cong khi » cong thai, khong khi, co khi
hang hoa » hang khoa, thanh hoa, hang va
so sach » so sanh, bo sach, co sach
su sach » vu sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( so sach tranh cong khi đong luc ) or ( su sach ((khanh hoa) OR (hang hoa)) phi đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so sach tranh cong khi đong luc ) OR ( su sach ((khanh hoa) OR (hang hoa)) phi đong luc ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( so sach tranh cong khi đong luc ) or ( su sach ((khanh hoa) OR (hang hoa)) phi đong luc ))*".