Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
sach tu » sach thu, cach tu, sach ty
hieu ve » hieu van
chu tre » cho tre, chu tri, cuu tre
nang xa » lang xa, nang ma, mang xa
cac do » cac don, cac doi, cac du
va chu » va che, va cau, va chi
do va » do van, so va

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 tu ((nang xa) or (nang x)) hoi. ((hieu ve) OR (hieu va)) cac do va hanh va chu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu ((nang xa) OR (nang x)) hoi. ((hieu ve) OR (hieu va)) cac do va hanh va chu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach tu ((nang xa) or (nang x)) hoi. ((hieu ve) OR (hieu va)) cac do va hanh va chu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach tu ((nang xa) or (nang x)) hoi. ((hieu ve) OR (hieu va)) cac do va hanh va chu tre*.