Perhaps you should try some spelling variations:
danh sai » dung sai, danh bat, danh dau
tu sach » thu sach, su sach, te sach
thu nam » tu nam, thu nhap, thu nhat
sach ky » sac ky, sach y, sach ty
hieu he » hieu ve, hiem he, hieu le
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
cua tre » cua te, cuu tre, cua triet
he nam » ha nam, nghe nam

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 ((nang ma) or (tang ma)) hoi. hieu he nam thu nam ((danh sai) or (dung tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang ma) OR (tang ma)) hoi. hieu he nam thu nam ((danh sai) OR (dung tai)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang ma) or (tang ma)) hoi. hieu he nam thu nam ((danh sai) or (dung tai)) cua tre*.