Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
danh vai » danh sai, danh va, doanh van
hieu van » thien van, lieu va, hieu ve
lang ha » long ha
lang xa » dang xay, lang van
sach le » cach le, sach de, sach lo
hieu va » lieu va, hieu qua
cau duc » cao duc, cau luc, chu duc
va danh » va dinh, va dan, va hanh
vai cua » dai cua, hai cua, lai cua
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: thu sach le ((lang xa) OR (lang ha)) hoi. ((hieu van) or (hieu va)) cau duc va danh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach le ((lang xa) OR (lang ha)) hoi. ((hieu van) OR (hieu va)) cau duc va danh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach le ((lang xa) OR (lang ha)) hoi. ((hieu van) or (hieu va)) cau duc va danh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach le ((lang xa) OR (lang ha)) hoi. ((hieu van) or (hieu va)) cau duc va danh vai cua tre*.