Perhaps you should try some spelling variations:
hang tai » hang va, dung tai
hanh tai » thanh tai, han tai, hinh tai
tu sach » thu sach, su sach, te sach
cuu tre » cua tre, cau tren, cau treo
hieu va » lieu va, hieu qua
cay tu » chay tu, cau tu, tay tu
va cay » va cac, va cao, va cai
my va » may va, ly va, me va
ky va » ly va, ke va, ky la

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