Perhaps you should try some spelling variations:
ban thanh » ban hang
hieu van » hieu va, thien van, lieu va
ban hanh » ban hang
ky tang » ky nang, kho tang, ky trong
ky dang » ky nang, ky danh
van cam » van nam, van lam, van cau
dai cuu » dai cua, dai huu
cuu tre » cua tre, cau tren, cau treo
su dai » sau dai, si dai, su tai

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

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