Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thanh vi » thanh va, thanh ve, nhanh vi
su sach » so sach, vu sach
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
cua tre » cua te, cuu tre, cua triet
y nang » ly nang, v nang, may nang
co hoi » co hoc, co loi

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 ((y nang) OR (ky nang)) co hoi. hieu van cau duc va ((thanh vi) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((y nang) OR (ky nang)) co hoi. hieu van cau duc va ((thanh vi) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((y nang) OR (ky nang)) co hoi. hieu van cau duc va ((thanh vi) or (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((y nang) OR (ky nang)) co hoi. hieu van cau duc va ((thanh vi) or (hanh vi)) cua tre*.