Perhaps you should try some spelling variations:
ban thanh » ban hang
ban hanh » ban hang
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cuu tre, cua triet
hai cua » thai cua, dai cua, hoi cua
van cam » van nam, van lam, van cau
cam duc » cam xuc, cao duc, pham duc
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
su sac » su sach, su cac, su xac

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sac ((ky lang) OR (ky dang)) xa hoi. hieu van cam duc ((ban thanh) or (ban hanh)) hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sac ((ky lang) OR (ky dang)) xa hoi. hieu van cam duc ((ban thanh) OR (ban hanh)) hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sac ((ky lang) OR (ky dang)) xa hoi. hieu van cam duc ((ban thanh) or (ban hanh)) hai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sac ((ky lang) OR (ky dang)) xa hoi. hieu van cam duc ((ban thanh) or (ban hanh)) hai cua tre*.