Perhaps you should try some spelling variations:
dung sai » dung tai, dung dat, dung ha
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
thu bac » thu ban, thu bao, tho bac
cua tre » cua te, cuu tre, cua triet
hieu he » hieu ve, hiem he, hieu le
cao hoi » cau hoi, co hoi, cao hoc
ty nang » ky nang, ty xang, ty hang
thu ba » thu ban, thu bao, thu ha
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: su sach ty nang cao hoi. hieu he nam ((thu ba) or (thu bac)) ((dung sai) OR (dung va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang cao hoi. hieu he nam ((thu ba) OR (thu bac)) ((dung sai) OR (dung va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty nang cao hoi. hieu he nam ((thu ba) or (thu bac)) ((dung sai) OR (dung va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty nang cao hoi. hieu he nam ((thu ba) or (thu bac)) ((dung sai) OR (dung va)) cua tre*.