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

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ly nang x hoi. hieu van ((cac dac) OR (cac dan)) ban ((hang dai) OR (hoang dai)) cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ly nang x hoi. hieu van ((cac dac) or (cac dan)) ban ((hang dai) OR (hoang dai)) cua tre~".
• Adding a wildcard symbol may retrieve word variants: su sach ly nang x hoi. hieu van ((cac dac) or (cac dan)) ban ((hang dai) OR (hoang dai)) cua tre*.