Perhaps you should try some spelling variations:
thieu sach » chieu sach, thien hach, theo sach
hieu cach » hieu cac, chieu sach, hieu ca
tranh cua » doanh cua, manh cua
dang cang » dang cong, dang bang, dang dang
thang ban » tang ban, thanh ban, tiang ban
cua dang » cua cong, cua ban
hang ban » hang luan, hang va, hang tai

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

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sach) OR (hieu cach)) - canh tranh cua dang cang ((thang ban) OR (hang ban)) can~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sach) or (hieu cach)) - canh tranh cua dang cang ((thang ban) OR (hang ban)) can~".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sach) or (hieu cach)) - canh tranh cua dang cang ((thang ban) OR (hang ban)) can*.