Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
su sach » so sach, vu sach
tai cua » thai cua, tai cuc, tri cua
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
dai hoi » dai hoc, dai hai, dai moi
cai hoi » cau hoi, cai hoa, lai hoi
luc va » duc va, tuc va
loc va » hoc va
ve coc » ve cuoc, ve cac, ve co

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 ky nang ((cai hoi) or (dai hoi)). hieu ve coc ((luc va) OR (loc va)) hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((cai hoi) OR (dai hoi)). hieu ve coc ((luc va) OR (loc va)) hanh tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((cai hoi) or (dai hoi)). hieu ve coc ((luc va) OR (loc va)) hanh tai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((cai hoi) or (dai hoi)). hieu ve coc ((luc va) OR (loc va)) hanh tai cua tre*.