Perhaps you should try some spelling variations:
thanh lai » thanh hai, thanh lap, thanh loi
hieu van » hieu va, thien van, lieu va
duc manh » suc manh, duc minh, duc tan
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
lang xa » lang ha, dang xay, lang van
long ha » dong ha, cong ha, dong hoa
lai cua » dai cua, hai cua, lai chau
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty ((lang xa) or (long ha)) hoi. hieu van nam ((duc manh) OR (duc anh)) thanh lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((lang xa) OR (long ha)) hoi. hieu van nam ((duc manh) OR (duc anh)) thanh lai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((lang xa) or (long ha)) hoi. hieu van nam ((duc manh) OR (duc anh)) thanh lai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((lang xa) or (long ha)) hoi. hieu van nam ((duc manh) OR (duc anh)) thanh lai cua tre*.