Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
sach thu » sach thue, sach thieu, sach tham
hieu van » hieu va, thien van, lieu va
hanh hai » nhanh hai, hang hai, hanh tai
van cac » van hac, van cau, van bac
cac duc » cac du, cao duc, cac dac
sach ty » sach y, sach tu, xach tay
cua tre » cua te, cuu tre, cua triet
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: su ((sach ty) OR (sach thu)) nang x hoi. hieu van cac duc va ((hanh hai) or (thanh hai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach thu)) nang x hoi. hieu van cac duc va ((hanh hai) OR (thanh hai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) OR (sach thu)) nang x hoi. hieu van cac duc va ((hanh hai) or (thanh hai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) OR (sach thu)) nang x hoi. hieu van cac duc va ((hanh hai) or (thanh hai)) cua tre*.