Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
bac cac » bac can, bac cao, bac cau
cac ban » cac dan, cac van, can ban
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
sach v » sach va, sach y, sach vay
sach 2 » sach y
va bac » van bac, va cac, va bai
x hoi » xa hoi, o hoi, x ho

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach v) OR (sach 2)) nang x hoi. hieu va bac cac ban ((doanh tai) or (thanh hai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach v) OR (sach 2)) nang x hoi. hieu va bac cac ban ((doanh tai) OR (thanh hai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach v) OR (sach 2)) nang x hoi. hieu va bac cac ban ((doanh tai) or (thanh hai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach v) OR (sach 2)) nang x hoi. hieu va bac cac ban ((doanh tai) or (thanh hai)) cua tre*.