Perhaps you should try some spelling variations:
ban hang » ngan hang
hieu van » hieu va, thien van, lieu va
hang dai » hoang dai, hang tai, hang dau
su sach » so sach, vu sach
sach ly » sach y, sach lo, sach ty
ly nang » ky nang, ly hang, ly vang
cac dac » cac dai, cac bac, cac tac
cua tre » cua te, cuu tre, cua triet

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ly nang x ho. hieu van ((cac dac) OR (cac dan)) ban hang dai cua tre~".
• Adding a wildcard symbol may retrieve word variants: su sach ly nang x ho. hieu van ((cac dac) OR (cac dan)) ban hang dai cua tre*.