Perhaps you should try some spelling variations:
quoc lan » quoc ban, nuoc luan, quoc quan
tu sach » thu sach, su sach, te sach
van cau » van dau, van hau, van chat
vai cua » dai cua, hai cua, lai cua
anh vai » anh va, anh bai, anh van
duc ban » duc tan, duc van, dua ban
thi van » thi lan, thi hanh, thi nang
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, dang xay
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: tu sach ky ((mang xa) or (nang ma)) hoi. thi van cau ((quoc lan) or (duc ban)) anh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((mang xa) OR (nang ma)) hoi. thi van cau ((quoc lan) OR (duc ban)) anh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((mang xa) or (nang ma)) hoi. thi van cau ((quoc lan) or (duc ban)) anh vai cua tre*.