Perhaps you should try some spelling variations:
nhanh hai » nhanh thai, thanh hai, nhanh ha
toc sach » hoc sach, doc sach, thuoc sach
sach thu » sach thue, sach thieu, sach tham
hanh hai » thanh hai, hang hai, hanh tai
cac duc » cac du, cao duc, cac dac
duc ban » duc tan, duc van, dua ban
hieu va » lieu va, hieu qua
mang xa » lang xa, mang may, dang xay
bang xa » lang xa, bang va, ang xa
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: toc sach thu ((bang xa) or (mang xa)) hoi. hieu va cac duc ban ((hanh hai) OR (nhanh hai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach thu ((bang xa) OR (mang xa)) hoi. hieu va cac duc ban ((hanh hai) OR (nhanh hai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach thu ((bang xa) or (mang xa)) hoi. hieu va cac duc ban ((hanh hai) OR (nhanh hai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach thu ((bang xa) or (mang xa)) hoi. hieu va cac duc ban ((hanh hai) OR (nhanh hai)) cua tre*.