Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
ban hanh » ban hang
hanh ca » hanh cac, hanh cat, hanh cua
duc ban » duc tan, duc van, dua ban
sach ty » sach y, sach tu, xach tay
va cao » va cac, va co, va dao
ca cua » co cua
ve cam » ve cham, ve cac, va cam
nang o » nang co, nang ho, nang ro
cua te » cua tu
o hoi » co hoi, o hoc, o hai

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 ty) OR (sach thu)) nang o hoi. hieu ((ve cam) or (va cao)) duc ban hanh ca cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach ty) OR (sach thu)) nang o hoi. hieu ((ve cam) OR (va cao)) duc ban hanh ca cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sach ty) OR (sach thu)) nang o hoi. hieu ((ve cam) or (va cao)) duc ban hanh ca cua te".
• Adding a wildcard symbol may retrieve word variants: so ((sach ty) OR (sach thu)) nang o hoi. hieu ((ve cam) or (va cao)) duc ban hanh ca cua te*.