Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
tinh van » trinh van, dinh van, tich van
tang ma » mang may, tang van
lang xa » lang ha, dang xay, lang van
cao duc » dao duc, cao suc, giao duc
tinh va » tich va, trinh van, trinh vat
cua tre » cua te, cuu tre, cua triet
va cao » va cac, va co, va dao

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 y ((tang ma) or (lang xa)) hoi. lieu va cao duc va ((tinh van) OR (tinh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y ((tang ma) OR (lang xa)) hoi. lieu va cao duc va ((tinh van) OR (tinh va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y ((tang ma) or (lang xa)) hoi. lieu va cao duc va ((tinh van) OR (tinh va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach y ((tang ma) or (lang xa)) hoi. lieu va cao duc va ((tinh van) OR (tinh va)) cua tre*.