Perhaps you should try some spelling variations:
thanh dat » thanh san, thanh hai, thanh van
thu sach » tu sach, thuat sach, thuoc sach
hanh tai » thanh tai, hang tai, han tai
hieu van » hieu va, thien van, lieu va
cac ban » cac dan, cac van, can ban
cam cac » ca cac, nam cac, cam chan
sach ky » sac ky, sach y, sach ty
van cam » van nam, van lam, van cau
tao hoi » tao khoi, tao boi, tay hoi
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang ((tao hoi) or (cau hoi)). hieu van cam cac ban ((thanh dat) or (hanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((tao hoi) OR (cau hoi)). hieu van cam cac ban ((thanh dat) OR (hanh tai)) cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((tao hoi) or (cau hoi)). hieu van cam cac ban ((thanh dat) or (hanh tai)) cua tre*.