Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh vai » hanh va, hanh tai, hanh van
toc sach » hoc sach, doc sach, thuoc sach
cuu ban » cuu van, cua ban, cuu san
cau cuu » cap cuu, cau cua, cau chu
van cau » van dau, van hau, van chat
dang ha » dong ha, dung ha, lang ha
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet
ha hoi » hoa hoi, ha noi, xa hoi

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) or (toc sach)) ky dang ha hoi. hieu van cau cuu ban ((hanh vai) OR (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky dang ha hoi. hieu van cau cuu ban ((hanh vai) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ky dang ha hoi. hieu van cau cuu ban ((hanh vai) OR (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky dang ha hoi. hieu van cau cuu ban ((hanh vai) OR (hanh vi)) cua tre*.