Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
cham duc » cham soc, pham duy, phan duc
tang van » dang van, hoang van, trong van
thanh va » thanh van, hanh va, thanh ha
trung ha » trung hoc, trung tam, trung cap
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua

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 y ((tang van) or (trung ha)) hoi. hieu va ((cham duc) OR (pham duc)) ban thanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((tang van) OR (trung ha)) hoi. hieu va ((cham duc) OR (pham duc)) ban thanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((tang van) or (trung ha)) hoi. hieu va ((cham duc) OR (pham duc)) ban thanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((tang van) or (trung ha)) hoi. hieu va ((cham duc) OR (pham duc)) ban thanh va cua tre*.