Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
kho tang » cao tang
cau tren » cu tren, dau tren, ca tren
ky sang » ky nang, ky dang, ky tang
lai hoi » dai hoi, lai hoa, lai roi
hieu ve » hieu va, hieu van
cac loc » cac lop, cac toc, cac hoc
ve cac » va cac, vien cac
loc va » hoc va, luc va
va dau » va dao
dau va » dau ve, lau va
va cau » van cau, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ((ky sang) or (kho tang)) lai hoi. hieu ve cac loc va dau va cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((ky sang) OR (kho tang)) lai hoi. hieu ve cac loc va dau va cau tren.
• Adding a wildcard symbol may retrieve word variants: thu sach ((ky sang) or (kho tang)) lai hoi. hieu ve cac loc va dau va cau tren*.