Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
sang tao » hang tai
hieu van » thien van, lieu va, hieu ve
te sach » toc sach
duc van » duc va, duc tan, duc manh
duc ban » duc tan, dua ban, duc man
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
tao hoi » tao khoi, tao boi, tay hoi
ky sang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet

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: te sach ky sang tao hoi. ((hieu van) OR (hieu va)) cau ((duc ban) OR (duc van)) thanh dai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky sang tao hoi. ((hieu van) OR (hieu va)) cau ((duc ban) or (duc van)) thanh dai cua tre~".
• Adding a wildcard symbol may retrieve word variants: te sach ky sang tao hoi. ((hieu van) OR (hieu va)) cau ((duc ban) or (duc van)) thanh dai cua tre*.